Caribbean Amphipoda (Crustacea) of Panama. Part V: parvorder Amphilochidira

57 Caribbean Amphipoda (Crustacea) of Panama. Part V: parvorder Amphilochidira Abigail R. Dugger1, Kristine N. White1 1 Georgia College & State University, Department of Biological and Environmental Sciences, Aquatic Sciences Center, Milledgeville, GA 31061 USA Corresponding author: Kristine N. White ([email protected]) Copyright: This is an open access article distributed under the terms of the CC0 Public Domain Dedication. Research Article Abstract The parvorder Amphilochidira includes 1,152 described species in 24 families. Amphilochidiran amphipods retain many plesiomorphic character states and are thought to represent the ancestral state of amphipods. Many amphipods in this parvorder cling to substrates such as algae or sponges. Nineteen species from four families within the parvorder are documented from Bocas del Toro, Panama, including one new species, Apolochus dragensis sp. nov. Range extensions are documented for eight species, including two species previously documented only from the Pacific Ocean. All species are diagnosed and an identification key to the Amphilochidira amphipods of Panama is provided herein. Resumen El parvorden Amphilochidira incluye 1,152 especies descritas en 24 familias. Los anfípodos Amphilochidira conservan muchos estados plesiomórficos y se cree que representan el estado ancestral de los anfípodos. Muchos anfípodos de este parvorden se adhieren a sustratos como algas o esponjas. Se documentan diecinueve especies de cuatro familias dentro del parvorden en Bocas del Toro, Panamá, incluyendo una nueva especie, Apolochus dragensis sp. nov. Se registran extensiones de distribución para ocho especies, incluyendo dos previamente documentadas solo en el Océano Pacífico. Se diagnostican todas las especies y se proporciona una clave de identificación para los anfípodos Amphilochidira de Panamá. Key words: Amphilochidae, Amphilochidira, Bocas del Toro, identification key, Leucothoidae, new species, Sebidae, Stenothoidae Introduction Amphilochidira Boeck, 1871 is a parvorder consisting of 1,152 species distributed worldwide (Horton et al. 2025). A synapomorphy shared by most families in the Amphilochidira is having the pereopod 4 carpus shorter than the propodus. Amphipods in the parvorder also share the following characteristics: sparsely setose antenna 2; gnathopod 2 simple, subchelate (chelate in Didymocheliidae Bellan-Santini & Ledoyer, 1987); pereopods 6 and 7 not extremely elongate; urosomites 1–3 separate (fused in Sebidae Walker, 1907), and an entire telson (Lowry and Myers 2017). Amphipods in this parvorder have retained many Academic editor: Alan Myers Received: 15 July 2025 Accepted: 4 October 2025 Published: 10 November 2025 ZooBank: https://zoobank. org/99283DDC-D767-43FB-9B159FFF59CDC7A4 Citation: Dugger AR, White KN (2025) Caribbean Amphipoda (Crustacea) of Panama. Part V: parvorder Amphilochidira. ZooKeys 1259: 57–102. https://doi.org/10.3897/ zookeys.1259.165130 ZooKeys 1259: 57–102 (2025) DOI: 10.3897/zookeys.1259.165130 This article is part of: Caribbean Amphipoda of Panama Edited by Kristine N. White 58 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama plesiomorphic character states, suggesting that this parvorder represents the ancestral state of amphipods, many of whom cling to substrates such as algae or sponges (Lowry and Myers 2017). According to Horton et al. (2025) the Amphilochidira comprises 24 families: Acanthonotozomatidae Stebbing, 1906 (11 spp.); Acanthonotozomellidae Coleman & Barnard, 1991 (8 spp.); Amathillopsidae Pirlot, 1934 (24 spp.); Amphilochidae Boeck, 1871 (93 spp.); Bolttsiidae Barnard & Karaman, 1987 (2 spp.); Cressidae Stebbing, 1899 (10 spp.); Cyproideidae Barnard, 1974 (46 spp.); Didymocheliidae (5 spp.); Dikwidae Coleman & Barnard, 1991 (2 spp.); Epimeriidae Boeck, 1871 (91 spp.); Iphimediidae Boeck, 1871 (105 spp.); Lafystiidae Sars, 1895 (6 spp.); Laphystiopsidae Stebbing, 1899 (8 spp.); Leucothoidae Dana, 1852 (205 spp.); Nihotungidae Barnard, 1972 (3 spp.); Ochlesidae Stebbing, 1910 (22 spp.); Odiidae Coleman & Barnard, 1991 (20 spp.); Pleustidae Buchholz, 1874 (141 spp.); Sebidae (25 spp.); Seborgiidae Holsinger, 1980 (in Holsinger and Longley 1980) (9 spp.); Sicafodiidae Just, 2004 (3 spp.); Stenothoidae Boeck, 1871 (284 spp.); Stilipedidae Holmes, 1908 (27 spp.); and Vicmusiidae Just, 1990 (2 spp.). Prior to this study, 37 Amphilochidiran species in six families were documented from Caribbean waters: Amphilochidae, Cyproideidae, Leucothoidae, Ochlesidae, Sebidae, and Stenothoidae (LeCroy et al. 2009; Miloslavich et al. 2010; Martín et al. 2013). Of the 37 species, eleven leucothoid species had been previously documented in Caribbean Panama (Anamixis cavatura Thomas, 1997; Anamixis vanga Thomas, 1997; Leucothoe ashleyae Thomas & Klebba, 2006; Leucothoe barana Thomas & Klebba, 2007; Leucothoe flammosa Thomas & Klebba, 2007; Leucothoe kensleyi Thomas & Klebba, 2006; Leucothoe laurensi Thomas & Ortiz, 1995; Leucothoe saron Thomas & Klebba, 2007; Leucothoe ubouhu Thomas & Klebba, 2007; Leucothoe tunica White, 2019 (as Leucothoe sp. C), and Leucothoe wuriti Thomas & Klebba, 2007). Leucothoe panpulco Barnard, 1961 was documented from the Pacific side of Panama at a depth of 3570 m (Barnard 1961). Nineteen Amphilochidiran species were collected during this study, including all but two of the leucothoid species previously reported from Panama (L. panpulco and L. saron). Materials and methods Coral rubble, sponges, ascidians, algae, sand, seagrass, hydroids, mangrove scrapings, and buoy scrapings were collected at 21 sites around Bocas del Toro, Panama at depths of 0–15 m. Coral rubble samples were elutriated with freshwater and other substrates were hand-picked to remove amphipods. Living amphipods were sorted into morphospecies, placed in clove oil for imaging, and preserved in 99.5% EtOH. Preserved specimens were examined in glycerol after being measured from the tip of the rostrum to the base of the telson. Amphipods were dissected using a stereomicroscope and illustrated using an Olympus BH2 differential interference contrast microscope with an Olympus BH2-DA drawing tube attached. Pencil drawings were digitally inked using a Wacom Intuos Pro Pen tablet following the methods of Coleman (2003) in Adobe Illustrator 2020. Abbreviations used in figures are as follows: H, habitus; Hd, head; A, antenna; C, coxa; G, gnathopod; P, pereopod; E, epimeron; Pl, pleopod; U, uropod; Ur, urosome; a, anamorph; l, leucomorph. Size ranges of each 59 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama species collected from Bocas del Toro, Panama are provided at the beginning of each material examined section. Specimens are deposited in the Smithsonian Institution, U.S. National Museum of Natural History (USNM), and the Gulf Coast Research Laboratory Museum (GCRL). Results Taxonomic account Parvorder Amphilochidira Boeck, 1871 Superfamily Amphilochoidea Boeck, 1871 Family Amphilochidae Boeck, 1871 Genus Apolochus Hoover & Bousfield, 2001 Diagnosis. Antenna 1 short, subequal in length with or slightly longer than peduncle of antenna 2, peduncle segments 1 and 2 broadened. Gnathopods 1 and 2 strongly subchelate. Gnathopod 2 carpus posterior lobe well-developed; propodus palm distinct, palmar angle defined by one or two spines. Pereopods 3 and 4 dactyli shorter than dactyli of pereopods 5–7. Telson subtriangular or linguiform. Apolochus dragensis sp. nov. https://zoobank.org/AC0AD314-A144-4BBE-BF61-C644E550B6D6 Figs 1–3, 22A ?Apolochus sp. A: LeCroy 2002: 231, fig. 237. ?Amphilochus neapolitanus: McKinney 1978: 137. ?Amphilochus neapolitanus: Thomas 1993: 24, fig. 25. Type locality. Bocas del Toro, Panama: Drago; 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble. Distribution. Panama: Bocas del Toro (present study). Material examined. Holotype: Panama • 1 ♀, 2.3 mm; Bocas del Toro, Drago; 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble; 9 Aug 2021; K.N. White leg.; USNM 1762913. Paratype: Panama • 1 ♀, 2.4 mm; Bocas del Toro, Swan Caye; 9.4536°N, 82.3000°W; depth 2 m; among coral rubble; 24 June 2023; K.N. White leg.; USNM 1762914. Diagnosis. Head anteroventral margin evenly rounded. Antenna 1 reaching the end of antenna 2 peduncle, with minute uni-articulate accessory flagellum. Mandibular molar reduced with a single apical spine. Gnathopod 2 carpal lobe nearly reaching palmar angle, propodus lacking anterolateral spines and anterodistal projection, anterodistal corner rounded, palm finely crenulate. Description. Female (holotype, 2.3 mm). Head. Eye medium, oval, darkly pigmented in the center. Head anteroventral margin evenly rounded; rostrum reaching end of antennae 1 peduncle article 1. Antenna 1 shorter than antenna 2, nearly reaching end of antenna 2 peduncle; flagellum 5-articulate; accessory flagellum uni-articulate, minute. Antenna 2 1.3 × length of antenna 1; flagellum 6-articulate. Maxilliped inner plate lined with marginal setae; outer plate broad, margins lined with setae, apical margin with one bifurcate spine-seta, inner margin slightly 60 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama U2 U1 T H Hd Figure 1. Apolochus dragensis sp. nov., female holotype, 2.3 mm, head, habitus, telson, uropod 1, and uropod 2. Scale bars: 0.5 mm. 61 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Xpd Mx2 G1 Mx1 RMd LMd G2 Figure 2. Apolochus dragensis sp. nov., female holotype, 2.3 mm, maxilla 2, gnathopod 1 lateral, maxilla 1, gnathopod 2 lateral, maxilliped, and left mandible; female paratype, 2.4 mm, right mandible. Scale bars: 0.5 mm. 62 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 3. Apolochus dragensis sp. nov., female holotype, 2.3 mm, pereopod 3, pereopod 4, pereopod 5, pereopod 6, pereopod 7, and pleopods 1–3. Scale bars: 0.5 mm. P5 P6 P7 P3 P4 Pl1–3 63 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama concave; palp article 3 inner distal margin tuberculate. Maxilla 1 inner plate with 5 marginal spine-setae, palp segment 2 elongate with 5 distal setae. Maxilla 2 plates medium width, both plates lined with thin and medium width setae apically. Mandibular molar reduced, with single apical spine; left mandible with row of nine spine setae; palp missing. Upper and lower lips damaged in dissection. Pereon. Coxae 1 short, ventral margin serrate; coxa 2 rounded, posteroventral margin serrate; coxa 3 anteriorly rounded, posteroventral margin serrate; coxa 4 rounded, posterior margin concave. Gnathopod 1 basis with one posteroventral seta; ischium as wide as long; carpal lobe reaching 0.67 × propodus posterior margin, distal margin with three setae; propodus palm convex, crenulate, with five setae in distal half; dactylus distal inner margin lined with setae. Gnathopod 2, basis bare; carpal lobe reaching palmar angle; propodus lacking anterolateral setae, anterodistal corner rounded, palm convex, crenulate, lined with small setae; dactylus slender, proximal margin lined with setae. Pereopods 3 and 4 dactyli medium, slender. Pereopods 5–7 bases rounded, pereopod 7 basis widest; dactylus medium, slender. Pleon. Epimera 1–3 rounded, bare. Pleopods, rami longer than peduncle; pleopods 1–3 rami with eight, seven, and six articles, respectively. Uropod 1 slender, peduncle with four marginal spine-setae, 1.6 × length of rami; rami subequal, distal margins lined with setae; inner ramus lacking spine-setae; outer ramus with one spine-seta. Uropod 2 0.5 × length of uropod 1; peduncle with one distal spine-seta, 0.5 × length of inner ramus; inner ramus 1.7 × length of outer ramus, with one distal spine-seta; outer ramus with one distal spine-seta. Uropod 3 missing. Telson subtriangular, length 2.4 × width, apex narrowly rounded. Variation (paratype female, 2.4 mm). Mandibular spine row with eleven spine setae. Male unknown. Etymology. After the place Drago, Bocas del Toro, Panama, meaning “mouth of the dragon” and referring to the type locality. Ecology and remarks. This species occurs among coral rubble at 2–3 m depth in Panama. This species is most likely the species called Amphilochus neapolitanus (Della Vale, 1893) from the western Atlantic and Caribbean Sea (McKinney 1978; Thomas 1993) and Apolochus sp. A (LeCroy 2002) based on the small, non-triturative molar and lack of anterolateral spines on the gnathopod 2 propodus. Apolochus dragensis sp. nov. can be differentiated from Apolochus neapolitanus based on the drawings from the Mediterranean illustrating a slightly triturative molar with two spines, a more densely setose uropod 2, and a wider telson (Krapp-Schickel 1982). The reduced molar and lack of anterolateral spines on the gnathopod 2 propodus easily distinguish this species from all other species documented from the region who have a triturative molar and anterolateral spines on the gnathopod 2 propodus (A. pillaii (Barnard & Thomas, 1983), A. cassahoya (McKinney, 1978), and A. delacaya (McKinney, 1978)). The new species shares a minute accessory flagellum on antenna 1 with A. pillaii, but A. cassahoya and A. delacaya have an accessory flagellum equal to the length of antenna 1 peduncle article 3. The new species shares a reduced molar with several other species but differs in the following ways: A. barnardi and A. staudei Hoover & Bousfield, 2001 have short, stout dactyls on pereopods 3 and 4 (vs medium length and slender); A. borealis (Enequist, 1949) has a short carpus on gnathopod 2 (vs reaching the palmar angle); and A. litoralis (Stout, 1912) has densely spinose 64 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 4. Apolochus cf. picadurus, female, 1.9 mm, gnathopod 2 lateral, pereopod 3, head, and antennae 1. Scale bars: 0.5 mm. P3 G2 Hd G2+ A1+ uropods (vs few spine-setae). The new species is also easily distinguished from the other Apolochus species diagnosed here in having a round head margin (vs acute in A. cf. picadurus (Barnard, 1962) and subquadrate in A. pillaii). Apolochus dragensis sp. nov. differs from all other described Apolochus species in having a reduced molar. Living specimens are translucent with tan coloration on anterior and posterior ends, white opaque coloration on anterior half, rust coloration on pereopods 6 and 7, red stripes on antennae, and red eyes. Apolochus cf. picadurus (Barnard, 1962) Figs 4, 22B Amphilochus picadurus Barnard, 1962: 126–129, fig. 4. Apolochus picadurus: Hoover and Bousfield 2001: 15. Material examined. Panama • 1–2 mm • 3 ♀; Bocas del Toro, Pigeon Key Reef; 9.2693°N, 82.2489°W; depth 0.5–1 m; among Halimeda and Thalassia; 9 Aug 2005; E. Baiser, T.A. Haney, S. LeCroy leg.; GCRL 6673 • 2 ♀; Bocas del Toro, Crawl Caye; 9.2476°N, 82.1290°W; depth 5–8 m; among coral rubble; 26 June 2023; K.N. White leg.; USNM 1762915. Diagnosis. Head anteroventral margin acute. Antenna 1 shorter than peduncle of antenna 2, lacking accessory flagellum. Gnathopod 2 carpal lobe nearly reaching palmar angle; propodus lacking anterolateral spines, with anterodistal projection. Pereopods 3 and 4 dactyli slender. 65 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Distribution. USA: Southern California (Barnard 1962); Panama: Bocas del Toro (present study). Ecology and remarks. This species occurs among coral rubble, Halimeda, and Thalassia at depths of 0.5–8 m in Panama and among green mud and rock in Southern California at depths from 3.6–36 m (Barnard 1962). Panamanian specimens agree closely with the original description. However, the mandibular molar was broken during dissection and cannot be confirmed in Panamanian specimens. The current distribution of this species is from central to Southern California (Barnard 1962). This finding extends the range of this species to include the Caribbean Sea. Analysis of more specimens is needed to confirm the species. Color of living specimens is unknown, ethanol-preserved specimens retain a brown spotted pattern. Apolochus pillaii (Barnard & Thomas, 1983) Figs 5, 22C Amphilochus pillaii Barnard & Thomas, 1983: 179–187, figs 1–3. Apolochus pillaii: Hoover and Bousfield 2001: 15; LeCroy 2002: 230, fig. 239. Material examined. Panama • 1.3 mm • 1 ♀; Bocas del Toro, Swan Caye; 9.4536°N, 82.3000°W; depth 2 m; among coral rubble; 24 June 2023; K.N. White leg.; USNM 1762916. Figure 5. Apolochus pillaii, female, 1.3 mm, pereopod 3, gnathopod 2 lateral, head, gnathopod 1 lateral. Scale bars: 0.5 mm. G1 G2 P3 Hd G2+ U3 72 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Anamixis cavatura Thomas, 1997 Figs 10, 23A, B Leucothoides pottsi: Shoemaker 1933: 249–250, fig. 3; Ledoyer 1967: 127, fig. 5b; Ruffo 1969: 12–13; Sivaprakasam 1967(1969): 373, fig. 1e–g; Ledoyer 1978a: 375; Ledoyer 1978b: 300–301; Ledoyer 1979a: 169; Ledoyer 1979b: 111, fig. 68(II); Thomas 1979: 107–109; Barnard 1979: 130. Anamixis pottsi: Ortiz and Lemaitre 1994: 124. Anamixis hanseni: Pearse 1912: 370; Thomas 1979: 107–109; Thomas and Taylor 1981: 462–467, figs 1–5; Thomas and Barnard 1983: 154–157 [not A. hanseni Stebbing, 1897]. Anamixis cavatura Thomas, 1997: 47–50, figs 3, 4; LeCroy 2007: 506, fig. 447; White 2011: 25, fig. 1. Material examined. Panama • 1.7–4.9 mm • 2 anamorph ♂; Bocas del Toro, Cayo Solarte; 9.3336°N, 82.2189°W; depth 2 m; among red algae and Halimeda; 07 Aug 2005; R. Collin, M. Faust, E. Gaiser, S. LeCroy, S. Richardson, M. Sorenson leg.; GCRL 6678 • 1 leucomorph ♀; Bocas del Toro, mangrove island next to Isla Solarte; depth 2 m; among coral rubble; 08 Aug 2021; K.N. White leg.; USNM 1762922 • 1 leucomorph ♀; Bocas del Toro, Drago Beach; 9.4181°N, 82.3375°W; depth 2–3 m; among red algae; 09 Aug 2021; K.N. White leg.; USNM 1762923 • 1 leucomorph ♀; Bocas del Toro, San Cristobal; 9.2625°N, 82.2350°W; depth 15 m; among coral rubble; 10 Aug 2021; K.N. White leg.; USNM 1762924 • 1 leucomorph ♂, 2 leucomorph ♀; Bocas del Toro, Crawl Caye; 9.2376°N, 82.1438°W; depth 1.5–3 m; among Halimeda; 11 Aug 2021; K.N. White leg.; USNM 1762925 • 1 anamorph ♂, 1 leucomorph ♂, 16 leucomorph ♀; Bocas del Toro, Crawl Caye; 9.2475°N, 82.1290°W; depth 5 m; among coral rubble; 12 Aug 2021; K.N. White leg.; USNM 1762926 • 1 anamorph ♂; Bocas del Toro, Hospital Point, 9.3319°N, 82.2148°W; depth 1–3 m; among Halimeda; 22 June 2023; K.N. White leg.; USNM 1762927 • 2 anamorph ♂; Bocas del Toro, Crawl Caye; 9.2459°N, 82.1369°W; depth 1–4 m; among coral rubble and Halimeda; 25 June 2023; K.N. White leg.; USNM 1762928 • 1 anamorph ♂; Bocas del Toro, Cayo Zapatilla 1; 9.2699°N, 82.0587°W; depth 10–11 m; among coral rubble; 28 June 2023; K.N. White leg.; USNM 1762929. Diagnosis. Anamorph male. Head anterior margin with small tooth-like projection; ventral keel elongate, subtriangular with pointed tip. Gnathopod 2 basis anteromedial margin with acute projection; propodus palm with several teeth; dactylus with distal serrations. Leucomorph male and female. Head anterior margin quadrate; ventral keel subrectangular. Gnathopod 1 carpus finely serrate, apex with two serrate spines, larger spine with bifid tip. Gnathopod 2 palm transverse, irregularly serrate. Distribution. USA: Dry Tortugas, Florida (Shoemaker 1933), Fort Pierce to Tampa, including the Florida Keys (Thomas 1997; LeCroy 2007), Mississippi Delta (Pearse 1912); Colombia: Isla Barú (Ortiz and Lemaitre 1994); Bahamas; Mexico: Yucatan; Belize: Carrie Bow Caye; Cuba: Guanahacabibes (Varela et al. 2003); Venezuela (Martín et al. 2013); Honduras; Jamaica; Greater and Lesser Antilles (Thomas 1997); Panama: Bocas del Toro (White 2011; present study). Ecology and remarks. This species occurs among red algae, Halimeda, and coral rubble at depths of 1–11 m. Panamanian anamorph males differ from the 73 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama original description in having the gnathopod 2 basis and ischium bare (vs each with one seta) and dactylus distally serrate (vs entire margin serrate). Living anamorphs are translucent white with brown splotches and have a red eye. Living leucomorphs are translucent white with magenta stripes. Anamixis vanga Thomas, 1997 Figs 11, 23C, D Anamixis vanga Thomas, 1997: 70–73, figs 17, 18; LeCroy 2007: 507, fig. 448; White 2011: 25–26, fig. 2. Material examined. Panama • 1–4 mm • 1 leucomorph ♂, 1 leucomorph ♀, 1 leucomorph juvenile; Bocas del Toro, Mangrove Inn; among coral rubble; 03 Aug 2005; M. Faust, E. Gaiser, T. Haney, S. Richardson, M. Sorenson leg.; GCRL 6679 • 3 anamorph ♂, 2 leucomoprh ♂, 6 leucomorph ♀; Bocas del Toro, Hospital Point; 9.3336°N, 82.2188°W; depth 15 m; among coral rubble and Halimeda; 06 Aug 2005; S. DeGrave, M. Salazar leg.; GCRL 6680 • 3 anamorph ♂, 2 leucomorph♀; Bocas del Toro, Cayo Solarte; 9.3336°N, 82.2189°W; depth 2 m; among sponges, coral rubble, and sand; 07 Aug 2005; R. Collin, M. Faust, E. Gaiser, S. LeCroy, S. Richardson, M. Sorenson leg.; GCRL 6681 • 1 anamorph ♂, Figure 10. Anamixis cavatura, leucomorph female (l), 3 mm, gnathopod 1 medial, gnathopod 2 medial, head; anamorph male (a), 3.1 mm, head, gnathopod 1 medial, gnathopod 2 medial; Scale bars: 0.5 mm. Hdl Hda G2a G1l G2l 74 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 11. Anamixis vanga, leucomorph female (l), 2.2 mm, head, gnathopod 2 medial, gnathopod 1 medial; anamorph male (a), 3.2 mm, head, gnathopod 2 medial. Scale bars: 0.5 mm. Hdl Hda G2a G1l G2l 2 leucomorph ♂, 6 leucomorph ♀; Bocas del Toro, Pigeon Key Reef; 9.2693°N, 82.2489°W; depth 0.5–1 m; among Halimeda and Thalassia; 09 Aug 2005; E. Baiser, T.A. Haney, S. LeCroy leg.; GCRL 6682 • 1 leucomorph ♀; Bocas del Toro, Isla Solarte; 9.2901°N, 82.1897°W; depth 1–5 m; among Halimeda; 08 Aug 2021; K.N. White leg.; USNM 1762930 • 2 leucomorph ♀; Bocas del Toro, Drago; 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble; 09 Aug 2021; K.N. White leg.; USNM 1762931 • 1 leucomorph ♀; Bocas del Toro, Pandora; 9.3278°N, 82.2222°W; depth 10 m; among coral rubble; 10 Aug 2021; K.N. White leg.; USNM 1762932 • 1 leucomorph ♀; Bocas del Toro, San Cristobal; 9.2849°N, 82.2945°W; depth 1–3 m; among Dictyota; 21 June 2023; K.N. White leg.; USNM 1762933 • 1 anamorph ♂, 1 leucomorph ♂, 6 leucomorph ♀; Bocas del Toro, Hospital Point; 9.3319°N, 82.2148°W; depth 1–3 m; among coral rubble; 22 June 2023; K.N. White leg.; USNM 1762934 • 2 leucomorph ♀; Bocas del Toro, Drago; 9.4134°N, 82.3334°W; depth 1–3 m; among coral rubble; 23 June 2023; K.N. White leg.; USNM 1762935 • 1 leucomorph ♀; Bocas del Toro, Swan Caye; 9.4536°N, 82.3000°W; depth 2 m; among coral rubble; 24 June 2023; K.N. White leg.; USNM 1762936 • 2 anamorph ♂, 1 leucomorph ♂, 4 leucomorph ♀; Bocas del Toro, Crawl Caye; 9.2476°N, 82.1290°W; depth 5–8 m; among coral rubble; 26 June 2023; K.N. White leg.; USNM 1762937 • 1 anamorph ♂; Bocas del Toro, Pandora; 9.3333°N, 82.2185°W; depth 7 m; among coral rubble; 26 June 2023; K.N. White leg.; USNM 1762938 • 2 leucomorph ♀; Bocas del Toro, STRI Dock; 9.3512°N, 82.2570°W; depth 0–1 m; dock scraping; 27 June 2023; 75 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama K.N. White leg.; USNM 1762939 • 1 leucomorph ♂, 3 leucomorph ♀; Bocas del Toro, Cayo Zapatilla 1; 9.2699°N, 82.0587°W; depth 10–11 m; among coral rubble; 28 June 2023; K.N. White leg.; USNM 1762940 • 1 anamorph ♂, 6 leucomorph♀; Bocas del Toro, Crawl Caye; 9.2502°N, 82.1318°W; depth 5–13 m; among coral rubble; 29 June 2023; K.N. White leg.; USNM 1762941. Diagnosis. Anamorph male. Head with lateral ridge, anterior margin concave, without anterodistal notch, ventral keel rectangular. Gnathopod 2 basis with acute process subdistally; propodus palm with three teeth. Leucomorph male and female. Head ocular lobe rounded; ventral keel rounded, subacute distally. Gnathopod 1 propodus margin finely serrate with several small setae; carpus dentate and finely serrate, terminal spines smooth with terminal bulb. Gnathopod 2 propodus palm oblique with several serrations. Distribution. USA: Georgia to the Florida Keys (Thomas 1997); Belize: Carrie Bow Caye (Thomas 1997); Mexico (Martín et al. 2013); Venezuela (Martín et al. 2013); Panama: Bocas del Toro (White 2011; present study). Ecology and remarks. This species occurs among sponges, Halimeda, Thalassia, and coral rubble at depths of 1–11 m. Thomas (1997) reported this species from solitary ascidians at depths to 20 m. Panamanian specimens agree closely with previous descriptions of the species. Anamorph males have an anterior tubercle on the gnathopod 2 basis that was not illustrated in original description as noted by White (2011). Living anamorphs and leucomorphs are translucent with pale brown stripes and have red eyes. Genus Leucothoe Leach, 1814 Diagnosis. Minimal sexual dimorphism. Eyes well-developed. Mandibular palp tri-articulate; left lacinia mobilis larger than right. Maxilliped outer plate not longer than palp article 1. Coxa 1–4 subequal in size. Gnathopod 1 carpochelate. Pereopods 5–7 bases expanded. Leucothoe alata Barnard, 1959 Figs 12, 23E Leucothoe minima Barnard, 1952: 9–12, pl. 1 [not Schellenberg, 1925: 141–142, fig. 12]. Leucothoe alata Barnard 1959: 19–20, pl. 1; Barnard 1962: 132, figs 7D–F; Barnard 1964a: 114; Barnard 1964b: 227; Barnard 1966: 22; Barnard 1969a: 164; Barnard 1969b: 214; Barnard 1979: 128–129; Hirayama 1985: 172–174, figs 166, 169. Material examined. Panama • 2.5–3.2 mm • 1 ♂, 1 ♀; Bocas del Toro, Cayo Zapatilla; 9.2699°N, 82.0587°W; depth 0 m; buoy scraping; 29 June 2023; K.N. White leg.; USNM 1762942. Diagnosis. Head anterodistal margin subquadrate without cusp; ventral keel slightly produced. Gnathopod 1 basis anterior and posterior margins bare; carpus thickened; propodus expanded, palm dentate; dactylus reaching less than 0.2 × propodus length. Gnathopod 2 basis with anterodistal projection; carpus distally truncate, spoon-like; propodus with one mediofacial setal row above 76 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama midline, reaching 0.9 × propodus length, palm with several small tubercles. Coxa 4 posterior margin slightly concave. Epimeron 3 posteroventral corner subquadrate. Distribution. USA: Monterey Bay to San Ramon Bay, California (Barnard 1952, 1955, 1962, 1964a, 1964b, 1966, 1969a, 1969b, 1979); Japan: West Kyushu, Tomioka Bay (Hirayama 1985); Panama: Bocas del Toro (present study). Ecology and remarks. This species occurs among sponges on docks (Barnard 1959) and buoys, suggesting that this species may be easily transported with fouling organisms. This may partially explain the range extension of this species to include the Caribbean Sea, when it was previously only documented from the Pacific Ocean. Panamanian specimens agree closely with the original description of this species, except for the anterodistal head margin appearing slightly more truncated in Panamanian specimens. The color of living specimens is unknown. Leucothoe ashleyae Thomas & Klebba, 2006 Figs 13, 23F Leucothoe ashleyae Thomas & Klebba, 2006: 14–16, figs 1–3, 7; LeCroy 2011: 626, fig. 515; White 2011: 26–27, fig. 3. Figure 12. Leucothoe alata, male, 2.5 mm, gnathopod 1 medial, head, coxa 4, epimeron 3, gnathopod 2 medial. Scale bars: 0.5 mm. Hd G1 G1+ C4 E3 G2 77 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 13. Leucothoe ashleyae, female, 3.6 mm, epimeron 3, coxa 4, gnathopod 1 medial, gnathopod 2 medial, head. Scale bars: 0.5 mm. E3 Hd C4 G1 G2 G1+ Material examined. Panama • 1–3 mm • 2 ♂; Bocas del Toro, STRI Point; 07 Aug 2005; S. DeGrave, M. Salazar leg.; GCRL 6683 • 4 juveniles; Bocas del Toro, Bastamientos; 07 Aug 2005; T.A. Haney leg.; GCRL 6684 • 1 ♀; Bocas del Toro, STRI Point; 9.3487°N, 82.2626°W; depth 12 m; among coral rubble; 06 Aug 2021; K.N. White leg.; USNM 1762943 • 2 ♂, 7 ♀; Bocas del Toro, Almirante; 9.2900°N, 82.3429°W; depth 10–11 m; commensal in Lissodendoryx columbiensis; 07 Aug 2021; K.N. White leg.; USNM 1762944 • 1 ♂, 1 ♀; Bocas del Toro, Swan Caye; 9.4536°N, 82.3000°W; depth 2 m; in sand; 24 June 2023; K.N. White leg.; USNM 1762945 • 4 ♂, 6 ♀, 3 juveniles; Bocas del Toro, Punta Caracol; depth 1–2 m; commensal in Lissodendoryx columbiensis and among Halimeda; 24 June 2023; K.N. White leg.; USNM 1762946 • 1 ♀; Bocas del Toro, Crawl Caye; 9.2476°N, 82.1290°W; depth 5–8 m; among coral rubble; 26 June 2023; K.N. White leg.; USNM 1762947 • 1 ♀; Bocas del Toro, Pandora; 9.3333°N, 82.2185°W; depth 7 m; among coral rubble; 26 June 2023; K.N. White leg.; USNM 1762948. Diagnosis. Head anterodistal margin rounded; ventral keel rounded. Gnathopod 1 basis anterior margin with 0–1 seta, posterior margin bare; propodus palm serrate; dactylus reaching more than 0.2 × propodus length. Gnathopod 2 basis anterior margin with six short setae; carpus distally expanded, anterior margin dentate; propodus primary mediofacial setal row above midline, reaching 0.7 × propodus length, secondary mediofacial row with two or three setae, 78 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama submarginal setal row present, palm with several small tubercles. Coxa 4 posterior margin slightly concave. Epimeron 3 posteroventral corner subquadrate. Distribution. USA: South Florida, Florida Keys; Bahamas; Puerto Rico: Vieques; Mexico (Martín et al. 2013); Belize: Whale Shoals; Honduras: Roatan (Thomas and Klebba 2006); Panama: Bocas del Toro (White 2011; present study). Ecology and remarks. This species occurs as a commensal in sponges and among coral rubble and algae at depths of 1–12 m. Panamanian specimens agree closely with previous descriptions of the species, with the exception of having gnathopod 1 coxa anterodistal corner smooth (vs serrate), carpus with distal setae (vs bare), and variation in the number of setae on gnathopod 2, remaining coxae, and pereopod 5–7 bases as noted by White (2011). Living specimens are translucent orange with a red eye. Leucothoe barana Thomas & Klebba, 2007 Figs 14, 23G Leucothoe barana Thomas & Klebba, 2007: 5–10, figs 1–3, 7A, B; LeCroy 2011: 628, fig. 519; White 2011: 27, 28, fig. 4. Material examined. Panama • 2–5 mm • 1 ♂, 1 ♀; Bocas del Toro, Crawl Cay; 9.2508°N, 82.1311°W; depth 0–2 m; commensal in Tedania sponge; 1 Aug 2005; J.D. Thomas leg.; GCRL 6685 • 1 ♀; Bocas del Toro, Swan Caye; 9.4533°N, 82.2148°W; depth 3 m; commensal in orange sponge; 04 Aug 2005; T. Haney leg.; GCRL 6686 • 5 ♂, 4 ♀, 1 juvenile; Bocas del Toro, STRI Point; depth 15 m; among coral rubble and Halimeda; 06 Aug 2005; S. DeGrave leg.; GCRL 6687 • 2 ♀; Bocas del Toro, Cayo Solarte; 9.3044°N, 82.1316°W; depth 1.5 m; among sponges, coral rubble, and sand; 07 Aug 2005; R. Collin, M. Faust, E. Gaiser, S. LeCroy, S. Richardson, M. Sorensen leg.; GCRL 6688 • 7 ♂, 6 ♀, 9 juveniles; Bocas del Toro, Laboratory Dock; 9.3512°N, 82.2570°W; depth 0.5 m; mangrove sponge; 08 Aug 2005; T.A. Haney leg.; GCRL 6689 • 2 ♂; Bocas del Toro, STRI Point; 9.3487°N, 82.2626°W; depth 12 m; commensal in loggerhead sponge; 06 Aug 2021; K.N. White leg.; USNM 1762949 • 2 ♀; Bocas del Toro, Drago; 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble; 09 Aug 2021; K.N. White leg.; USNM 1762950 • 1 ♀, 1 juvenile; Bocas del Toro, Drago; 9.4134°N, 82.3334°W; depth 1–3 m; among sponges and coral rubble; 23 June 2023; K.N. White leg.; USNM 1762951 • 1 ♀, 1 juvenile; Bocas del Toro, Punta Caracol; depth 1–2 m; commensal in Lissodendoryx columbiensis; 24 June 2023; K.N. White leg.; USNM 1762952. Diagnosis. Head anterodistal margin quadrate with cusp; ventral keel projected with cusp. Coxae 1–4 anterodistal and/or ventral margins serrate; coxa 4 posterior margin tapered. Gnathopod 1 basis anterior and posterior margins setose; carpus with two facial setae; propodus palm dentate; dactylus reaching greater than 0.2 × propodus length. Gnathopod 2 basis anterior margin lined with setae; carpus distally truncate; propodus mediofacial setal row reaching 0.7 × propodus length, secondary mediofacial row with six setae, palm with several tubercles. Epimeron 3 posteroventral corner narrowly rounded. Distribution. USA: Florida Keys; Belize: Pelican Cays (Thomas and Klebba 2007); Panama: Bocas del Toro (White 2011; present study). 79 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Ecology and remarks. This species occurs as a commensal in sponges and among coral rubble and algae at depths of 1–12 m. Panamanian specimens agree closely with previous descriptions of this species with the exception of coxa 4 having a smooth anterior margin (vs having two sharp cusps in original description). Living specimens are translucent purple in color with a red eye. Leucothoe flammosa Thomas & Klebba, 2007 Figs 15, 23H Leucothoe spinicarpa Ortiz 1975: 8. Leucothoe flammosa Thomas & Klebba, 2007: 10–15, figs 4–6, 7C, D; LeCroy 2011: 629, fig. 505; White 2011: 28–29, fig. 5. Material examined. Panama • 4.5–6.5 mm • 1 ♂, 1 ♀; Bocas del Toro, STRI Point; 9.3487°N, 82.2626°W; depth 12 m; commensal in Lima scabra; 06 Aug 2021; K.N. White leg.; USNM 1762953 • 1 ♂, 2 ♀; Bocas del Toro, Almirante; 9.2900°N, 82.3429°W; depth 10–11 m; commensal in Lima scabra; 07 Aug 2021; K.N. White leg.; USNM 1762954 • 3 ♀; Bocas del Toro, Almirante; 9.2900°N, 82.3429°W; depth 10–11 m; from ark clams; 07 Aug 2021; K.N. White leg.; USNM 1762955. Diagnosis. Head anteroventral margin round. Coxae 1–4 smooth; coxa 4 posterior margin rounded. Gnathopod 1 basis expanded, posterior margin lacking setae; carpus expanded, posterior margin with row of long setae; propodus Figure 14. Leucothoe barana, female, 5.5 mm, gnathopod 1 medial, head, epimeron 3, coxa 4, gnathopod 2 medial. Scale bars: 0.5 mm. Hd G1 C4 E3 G2 80 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Hd G1 G2 E3 C4 Figure 15. Leucothoe flammosa, male, 5 mm, gnathopod 1 medial, epimeron 3, head, coxa 4, gnathopod 2 medial. Scale bars: 0.5 mm. palm smooth; dactylus reduced, nail-like. Gnathopod 2 basis with few setae; carpus narrowing distally, tridentate; propodus mediofacial setal row above midline, reaching 0.6 × length of propodus, dense row of submarginal setae present, palm with several tubercles; dactylus reaching 0.5 × length of propodus. Epimeron 3 posteroventral margin subquadrate, with a single seta. Distribution. USA: Florida Keys (Thomas and Klebba 2007); Belize: Pelican Cays (Thomas and Klebba 2007); Cuba: Gulf of Batabanó and Baracoa Beach, Barlovento (Ortiz 1975); Panama: Bocas del Toro (White 2011; present study). Ecology and remarks. This species occurs in the mantle cavities of bivalve mollusks at depths of 1–20 m. Panamanian specimens differ from the original description in being generally less setose (specifically on coxae and epimera) and lacking setae on gnathopod 1 basis posterior margin. White (2011) illustrated specimens of L. flammosa from Panama with fewer shorter setae on the gnathopod 1 basis posterior margin, suggesting that this character may vary within the species. Living specimens are translucent white with brown eyes. Ommatidia separated with white coloration. Females have yellow-green eggs. Leucothoe kensleyi Thomas & Klebba, 2006 Figs 16, 24A Leucothoe tridens: Barnard 1965: 492; 1970: 211, fig. 137; 1971: 103; Serejo 1998: 109–112, figs 3, 4 [not Leucothoe tridens Stebbing, 1888]. 81 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 16. Leucothoe kensleyi, male, 4.8 mm, head, gnathopod 2 medial, epimeron 3, coxa 4, gnathopod 1 medial, pereopod 7. Scale bars: 0.5 mm. Hd G2 E3 C4 G1 P7 Leucothoe kensleyi Thomas & Klebba, 2006: 17–22, figs 4–7; LeCroy 2011: 631, fig. 509; White 2011: 29–30, fig. 6. Material examined. Panama • 4–5.6 mm • 1 ♀; Bocas del Toro, Juan Point; 9.3015°N, 82.2940°W; depth 10 m; among coral rubble; 07 Aug 2021; K.N. White leg.; USNM 1762956 • 1 ♂; Bocas del Toro, Drago 9.4181°N, 82.3375°W; depth 2–3 m; among coral rubble; 09 Aug 2021; K.N. White leg.; USNM 1762957 • 1 ♂, 1 ♀, 1 juvenile; Bocas del Toro, Hospital Point; 9.3319°N, 82.2148°W; depth 1–3 m; among coral rubble; 22 June 2023; K.N. White leg.; USNM 1762958 • 4 ♀; Bocas del Toro, Crawl Caye; 9.2459°N, 82.1369°W; depth 1–4 m; among coral rubble; 25 June 2023; K.N. White leg.; USNM 1762959. Diagnosis. Head anterodistal margin quadrate with cusp; ventral keel acute. Coxae 1–3 each with anteroand posterodistal cusp, coxa 4 ventrally serrate, posteriorly tapered. Gnathopod 1 basis anterior margin with few setae, posterior margin bare; carpus with one facial seta; propodus palm dentate; dactylus reaching greater than 0.2 × propodus length. Gnathopod 2 basis anterior margin with few setae; carpus tapering distally; propodus mediofacial setal row above midline, reaching 0.7 × propodus length, secondary mediofacial row with 2–4 setae, palm with several small tubercles. Pereopod 5–7 bases narrowly expanded. Epimeron 3 posteroventral corner quadrate. Distribution. USA: Hawaii (Thomas and Klebba 2006), South Carolina (LeCroy 2011), South Florida to the Florida Keys (Thomas and Klebba 2006); Mexico (Martín et al. 2013); Belize: Carrie Bow Cay (Thomas and Klebba 2007); 88 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 21. Leucothoe wuriti, male, 6.7 mm, gnathopod 1 medial, coxa 4, epimeron 3, head, gnathopod 2 medial. Scale bars: 0.5 mm. Hd G1 G1+ C4 E3 G2 pital Bight; 9.3045°N, 82.1316°W; depth 1.5 m; among sponges, coral rubble and sand; 7 Aug 2005; R. Collin, M. Faust, E. Gaiser, S. LeCroy, S. Richardson, M. Sorensen leg.; GCRL 6701 • 1 ♀; Bocas del Toro, Laboratory Dock; 9.3511°N, 82.2570°W; depth 1 m; light trap; 8 Aug 2005; S. DeGrave leg.; GCRL 6702 • 2 juveniles; Bocas del Toro, Weather Instrument Platform; 9.3333°N, 82.2185°W; depth 1 m; commensal in lavender sponge; 8 Aug 2005; T.A. Haney leg.; GCRL 6703 • 1 ♂, 3 ♀; Bocas del Toro, Isla Solarte; 9.2901°N, 82.1897°W; depth 1–5 m; commensal in ascidian and mangrove scraping; 8 Aug 2021; K.N. White leg.; USNM 1762975. Diagnosis. Head anterior margin rounded; ventral keel anterodistal margin quadrate. Gnathopod 1 coxa with one mediofacial seta; basis anterior margin with few short setae, posterior margin bare; carpus proximal margin dentate, with several facial setae; propodus palm dentate; dactylus reaching more than 0.2× propodus length. Gnathopod 2 basis anterior margin with several short setae, posterior margin bare; carpus distally truncate, anterior margin dentate; propodus primary mediofacial setal row displaced to midline, reaching 0.8 × propodus length, secondary mediofacial setal row with three setae, palm with distinct tubercules, one row of submarginal setae present. Coxa 4 smooth, posterior margin concave. Epimeron 3 posteroventral corner subquadrate, slightly produced. 89 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 22. Photographs of living specimens unless noted. A. Apolochus dragensis sp. nov.; B. Apolochus pillaii; C. Apolochus cf. picadurus (ethanol-preserved specimen); D. Seba cf. tropica (ethanol-preserved specimen); E. Stenothoe gallensis; F. Stenothoe minuta; G. Stenothoe valida (ethanol-preserved specimen). Scale bars: 1.0 mm. A B C D E F G 90 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Figure 23. Photographs of live specimens unless noted. A. Anamixis cavatura anamorph; B. Anamixis cavatura leucomorph; C. Anamixis vanga anamorph (ethanol-preserved specimen); D. Anamixis vanga leucomorph; E. Leucothoe alata (ethanol-preserved specimen); F. Leucothoe ashleyae; G. Leucothoe barana; H. Leucothoe flammosa. Scale bars: 1.0 mm. A B CD EF GH 91 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Distribution. USA: Biscayne Bay, Florida Keys (Thomas and Klebba 2007); Belize: Pelican Cays (Thomas and Klebba 2007); Panama: Bocas del Toro (White 2011; present study). Figure 24. Photographs of living specimens unless noted. A. Leucothoe kensleyi; B. Leucothoe laurensi; C. Leucothoe machidai (ethanol-preserved specimen); D. Leucothoe tunica (ethanol-preserved specimen); E. Leucothoe ubouhu; F. Leucothoe wuriti. Scale bars: 1.0 mm. A B C D EF 92 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Ecology and remarks. This species occurs as commensal in ascidians and among sponges, coral rubble, Halimeda, and sand at depths of 0–15 m. Panamanian specimens agree closely with the original description except for a shorter facial seta on gnathopod 1 coxa (see White 2011 for other variations in these specimens). Living specimens are translucent white with maroon stripes on antenna 1 and along pereonite edges. Identification Key to the Caribbean Amphilochidira of Panama 1 Eyes absent or poorly developed; gnathopods 1 and 2 chelate; urosome segments 2 and 3 fused (Fig. 6)...........................................Seba cf. tropica – Eyes present, well-developed (Fig. 1); gnathopods 1 and 2 carpochelate (Fig. 11) or subchelate (Fig. 2); urosome segments 1–3 separate (Fig. 8)...2 2 Coxa 4 extensively broadened (Fig. 8); pereopod 5 basis not expanded (Fig. 9); uropod 3 uniramous (Fig. 8) ............................................................3 – Coxa 4 not extensively broadened (Fig. 19); pereopod 5 basis expanded (Fig. 18); uropod 3 biramous (Fig. 5) ............................................................5 3 Gnathopod 2 propodus palmar angle present; uropod 1 inner ramus bare; uropod 3 second article of ramus 1.6× length of first article of ramus (Fig. 8) ................................................................................ Stenothoe minuta – Gnathopod 2 propodus palmar angle absent; uropod 1 inner ramus with at least one spine-seta; uropod 3 second article of ramus subequal in length with first article of ramus (Figs 7, 9) ............................................................4 4 Eye small; pereopod 7 merus posterodistal lobe not reaching more than halfway to distal margin of carpus; uropod 1 peduncle with distoventral spur (Fig. 7) .....................................................................Stenothoe gallensis – Eye large; pereopod 7 merus posterodistal lobe expanded, nearly reaching distal margin of carpus; uropod 1 peduncle lacking distoventral spur (Fig. 9) ..................................................................................Stenothoe valida 5 Antenna 1 shorter than antenna 2 (Fig. 1); gnathopod 1 subchelate; propodus with single row of simple robust setae along entire palmar margin (Fig. 5) ............................................................................................................6 – Antenna 1 subequal in length with or longer than antenna 2; gnathopod 1 carpochelate; propodus lacking simple robust setae along entire palmar margin (slender setae may be present) (Fig. 21) ........................................8 6 Head anteroventral angle acute; antenna 1 lacking accessory flagellum; gnathopod 2 propodus with small anterodistal projection (Fig. 4) .............. ................................................................................. Apolochus cf. picadurus – Head anteroventral angle subquadrate or rounded; antenna 1 with minute uni-articulate accessory flagellum (Fig. 1); gnathopod 2 propodus lacking anterodistal projection (Fig. 2) .....................................................................7 7 Head anteroventral angle rounded (Fig. 1); gnathopod 2 carpal lobe nearly reaching propodus palmar angle; propodus lacking antero-lateral spines, anterodistal margin rounded (Fig. 2) ............Apolochus dragensis sp. nov. – Head anteroventral angle subquadrate; gnathopod 2 carpal lobe not reaching propodus palmar angle; propodus with antero-lateral spines, anterodistal margin acute (Fig. 5) .......................................... Apolochus pillaii 93 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama 8 Gnathopod 1 carpus and propodus each with long apical seta (Fig. 10G1a); gnathopod 2 ischium elongate, length at least 2× width (Fig. 10G2a) ......9 – Gnathopod 1 carpus and propodus lacking long apical setae (Fig. 10G1l); gnathopod 2 ischium not elongate, length < 2× width (Fig. 10G2l) .........10 9 Head anterior margin rounded, anterodistal margin with cusp, without lateral ridge; ventral keel ventrally triangular; gnathopod 2 dactylus proximal margin with two large tubercles, distally serrate (Fig. 10) ............................ ................................................................Anamixis cavatura anamorph male – Head anterior margin excavate, anterodistal margin without cusp, with lateral ridge; ventral keel ventrally quadrate; gnathopod 2 dactylus proximal margin with one large tubercle, distally smooth (Fig. 11) ............................ .................................................................... Anamixis vanga anamorph male 10 Gnathopod 1 carpus apex with spines (Fig. 10G1l); gnathopod 2 propodus subtriangular (Fig. 10G2l) ...........................................................................11 – Gnathopod 1 carpus apex without spines; gnathopod 2 propodus subovate or subrectangular (Fig. 19) .................................................................12 11 Head anterior margin truncate; ventral keel projected upward; gnathopod 1 carpus proximal margin dentate, apex with two dentate embedded spines, larger spine distally bifid; gnathopod 2 propodus palm nearly transverse (Fig. 10l) ............................ Anamixis cavatura leucomorph male or female – Head anterior margin rounded; gnathopod 1 carpus proximal margin serrate, apex with two smooth embedded spines, larger spine distally expanded; gnathopod 2 propodus palm oblique (Fig. 11l) ............................... ................................................Anamixis vanga leucomorph male or female 12 Gnathopod 1 stout, propodus inflated; gnathopod 2 mediofacial setal row reaching almost entire length of propodus above midline (Figs 12, 17) ....13 – Gnathopod 1 linear, propodus straight; gnathopod 2 mediofacial setal row reaching 0.8× length of propodus or less, at least slightly displaced toward midline (Figs 13, 19) ....................................................................................14 13 Gnathopod 1 carpus with long distal seta, dactylus longer than 0.2× propodus length; gnathopod 2 propodus with large distal blade-like tooth, carpus reaching palmar margin, narrowing distally (Fig. 17) ....................... ..........................................................................................Leucothoe laurensi – Gnathopod 1 carpus without long distal seta, dactylus shorter than 0.2× propodus length; gnathopod 2 propodus without large distal bladelike tooth, carpus not reaching palmar margin, distal margin spoon-like (Fig. 12) ................................................................................. Leucothoe alata 14 Gnathopod 1 basis proximally inflated, carpus with long distal setae; propodus palm smooth; dactylus reaching < 0.2× propodus length, naillike; gnathopod 2 propodus with dense submarginal setae, palm defined by notch for insertion of dactylus; dactylus reaching ~0.5× propodus length (Fig. 15)..............................................................Leucothoe flammosa – Gnathopod 1 basis straight, carpus lacking long distal setae; propodus palm with ornamentation; dactylus reaching > 0.2× propodus length; gnathopod 2 propodus with sparse submarginal setae, palm not defined by notch for insertion of dactylus; dactylus reaching > 0.5× propodus length (Figs 19, 21) .................................................................................................15 94 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama 15 Coxa 1 with mediofacial seta; gnathopod 2 propodus mediofacial setal row strongly displaced to midline, reaching 0.8× propodus length, palm with deep indentation between large projections (Fig. 21) ..........Leucothoe wuriti – Coxa 1 lacking mediofacial seta; gnathopod 2 propodus mediofacial setal row above midline, may be slightly displaced toward midline, reaching < 0.8× propodus length, palm without deep indentation (Fig. 13) ..............16 16 Head anterior margin evenly rounded; ventral keel anterior margin deeply concave, anteroventral margin rounded; gnathopod 2 carpus strongly expanded (Figs 13, 19) ...................................................................................17 – Head anterior margin truncate; ventral keel anterior margin straight or weakly concave, anteroventral margin quadrate or subquadrate; gnathopod 2 carpus rounded, tapered, or slightly expanded (Figs 14, 16) .........18 17 Gnathopod 1 propodus palm serrate; gnathopod 2 carpus distal margin oblique; coxa 4 posterior margin strongly concave (Fig. 13) ....................... .........................................................................................Leucothoe ashleyae – Gnathopod 1 propodus palm dentate; gnathopod 2 carpus distal margin rounded; coxa 4 posterior margin weakly concave/tapered (Fig. 19) ......... .............................................................................................Leucothoe tunica 18 Head anteroventral margin with acute cusp; ventral keel with acute cusp; coxa 4 ventral margin tapered, serrate; pereopods 5–7 bases narrowly expanded, length > 1.4× width (Fig. 16) .........................................................19 – Head anteroventral margin without pronounced cusp; ventral keel without pronounced cusp; coxa 4 ventral margin rounded, smooth; pereopods 5–7 bases widely expanded, length < 1.4× width (Fig. 20) ..............................20 19 Ventral keel anterior margin oblique, projecting forward; gnathopod 1 carpus with three distolateral facial setae; coxa 4 anteroventral corner rounded; epimeron 3 posteroventral margin rounded (Fig. 14) ........ Leucothoe barana – Ventral keel anterior margin straight; gnathopod 1 carpus lacking distolateral facial setae; coxa 4 anteroventral corner acute; epimeron 3 posteroventral margin quadrate (Fig. 16) ...................................Leucothoe kensleyi 20 Ventral keel anterior margin slightly convex, anteroventral margin serrate; female gnathopod 1 basis posterior margin bare; gnathopod 2 carpus distally rounded; coxa 4 posterior margin tapered (Fig. 18) ....................... ......................................................................................Leucothoe machidai – Ventral keel anterior margin straight, anteroventral margin smooth; female gnathopod 1 basis posterior margin with several long setae; gnathopod 2 carpus slightly expanded and oblique distally; coxa 4 posterior margin concave (Fig. 20) .............................................................. Leucothoe ubouhu Discussion This study documents a range extension for eight amphilochidiran amphipod species to include the Caribbean waters of Panama. Three species now have a distribution pattern including both the Pacific and Caribbean (Apolochus cf. picadurus, Leucothoe alata, and Leucothoe kensleyi). These distribution patterns may suggest that these species were established before the isthmus of Panama closed or may more likely be due to the clinging and commensal lifestyle of these species. These amphipods may be introduced to new areas with fouling 95 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama organisms on ships traveling through the Panama Canal. Apolochus dragensis sp. nov. is described herein, increasing the known members of the genus to 16 species. This study increases the known number of amphilochidiran amphipods from Caribbean Panama from 12 to 21 species. The Caribbean Amphipoda of Panama identification key is available online: https://www.invertebase. org/portal/ident/key.php?clid=58&pid=4&dynclid=0&taxon=All+Species (Caribbean Amphipoda of Panama, 2025). Acknowledgments Logistical support and facilities were provided by Georgia College & State University Department of Biological and Environmental Sciences and the Smithsonian Tropical Research Institute (STRI). Special thanks to Carolina Cesar and Valentina Cardona for assistance with diving and collecting in Bocas del Toro. The authors also wish to thank Dr. Lauren Hughes and the Amphipod Taxonomy Course members for collecting assistance in 2023. Special thanks go to Sara LeCroy for her loan of specimens collected in 2005. Suggestions from two anonymous reviewers greatly improved the quality of this manuscript. Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Use of AI No use of AI was reported. Funding Funding for this study was provided by a National Science Foundation grant: Collaborative Research: ARTS: Understanding Tropical Invertebrate Diversity Through Integrative Revisionary Systematics and Training (1856421). Author contributions Conceptualization: KNW. Data curation: ARD, KNW. Formal analysis: KNW. Funding acquisition: KNW. Investigation: ARD, KNW. Methodology: KNW. Project administration: KNW. Supervision: KNW. Writing – original draft: ARD, KNW. Writing – review and editing: KNW, ARD. Author ORCIDs Abigail R. Dugger https://orcid.org/0009-0007-9032-2052 Kristine N. White https://orcid.org/0000-0002-5203-1656 Data availability All of the data that support the findings of this study are available in the main text. 96 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama References Barnard KH (1930) Crustacea. Part XI. – Amphipoda. British Antarctic (“Terra Nova”) Expedition, 1910. Natural History Report. Zoology: Analysis of Complex Systems, ZACS 8(4): 307–454. Barnard JL (1952) Some Amphipoda from Central California. The Wasmann Journal of Biology 10(1): 9–36. Barnard JL (1955) Two new spongicolous amphipods (Crustacea) from California. Pacific Science 9: 26–30. https://archive.org/details/biostor-234659 Barnard JL (1959) Estuarine Amphipoda. In: Barnard JL, Reish DJ (Eds) Ecology of Amphipoda and Polychaeta of Newport Bay, California. Allan Hancock Foundation Publications, Occasional Paper 21: 13–69. https://doi.org/10.25549/hancock-c82-19368 Barnard JL (1961) Gammaridean Amphipoda from depths of 400 to 6000 m. Galathea Report 5: 23–128. Barnard JL (1962) Benthic marine Amphipoda of southern California: Families Amphilochidae, Leucothoidae, Stenothoidae, Argissidae, Hyalidae. Pacific Naturalist 3(3): 116–163. Barnard JL (1964a) Marine Amphipoda of Bahia de San Quintin, Baja California. Pacific Naturalist 4(3): 55–139. Barnard JL (1964b) Los anfipodos bentonicos marinos de la costa occidental de Baja California. Revista de la Sociedad Mexicana de Historia Natural 24: 205–274. Barnard JL (1965) Marine Amphipoda of atolls in Micronesia. Proceedings of the United States National Museum 117(3516): 459–552. https://doi.org/10.5479/ si.00963801.117-3516.459 Barnard JL (1966) Benthic Amphipoda of Monterey Bay, California. Proceedings of the United States National Museum 119(3541): 1–41. https://doi.org/10.5479/ si.00963801.119-3541.1 Barnard JL (1969a) A biological survey of Bahía de Los Angeles, gulf of California, Mexico, IV: Benthic Amphipoda (Crustacea). Transactions of the San Diego Society for Natural History 15: 175–228. https://doi.org/10.5962/bhl.part.12057 Barnard JL (1969b) Gammaridean Amphipoda of the Rocky Intertidal of California: Monterey Bay to La Jolla. United States National Museum Bulletin 258: 1–230. https:// doi.org/10.5479/si.03629236.258.1 Barnard JL (1970) Sublittoral Gammaridea (Amphipoda) of the Hawaiian Islands. Smithsonian Contributions to Zoology 34(34): 1–286. https://doi.org/10.5479/ si.00810282.34 Barnard JL (1971) Keys to the Hawaiian marine Gammaridea, 0–30 meters. Smithsonian Contributions to Zoology 58(58): 1–135. https://doi.org/10.5479/si.00810282.58 Barnard JL (1972) A review of the family Synopiidae (= Tironidae), mainly distributed in the deep sea (Crustacea: Amphipoda). Smithsonian Contributions to Zoology 124(124): 1–94. https://doi.org/10.5479/si.00810282.124 Barnard JL (1974) Gammaridean Amphipoda of Australia, Part II. Smithsonian Contributions to Zoology 139(139): 1–148. https://doi.org/10.5479/si.00810282.139 Barnard JL (1979) Littoral Gammaridean Amphipoda from the Gulf of California and the Galapagos Islands. Smithsonian Contributions to Zoology 271(271): 1–149. https:// doi.org/10.5479/si.00810282.271 Barnard JL, Karaman GS (1987) Revisions in Classification of Gammaridean Amphipoda (Crustacea) Part 3. Proceedings of the Biological Society of Washington 100(4): 856–875. https://biostor.org/reference/74783 97 ZooKeys 1259: 57–102 (2025), DOI: 10.3897/zookeys.1259.165130 Abigail R. Dugger and Kristine N. White: Amphilochidira of Panama Barnard JL, Thomas JD (1983) A new species of Amphilochus from the gorgonian Pterogorgia anceps in the Caribbean Sea. In: John PA (Ed.) Selected Papers on Crustacea. The Aquarium, Trivandrum, 179–187. Bate CS (1863) Catalogue of the Amphipodous Crustacea in the Collection of the British Museum. British Museum of Natural History, London, 399 pp. Bellan-Santini D, Ledoyer M (1987) Gammariens (Crustacea, Amphipoda) des îles Marion et Prince Edward. Campagne MD 08 du M. S. ‘’Marion Dufresne’’ en 1976. Bollettino del Museo Civico di Storia Naturale di Verona 13: 349–435. https://www.marinespecies.org/amphipoda/aphia.php?p=sourcedetails&id=345514 Boeck A (1871) Crustacea Amphipoda borealia et arctica. Forhandlinger i Videnskabs-Selskabet i Christiania 1870: 83–280. https://doi.org/10.5962/bhl.title.2056 Bousfield EL (1973) Shallow-Water Gammaridean Amphipoda of New England. Cornell University Press, Ithaca, New York, 312 pp. Buchholz R (1874) Crustaceen. Die zweite Deutsche Nordpolarfahrt in den Jahren 1869 und 1870, unter Führung des Kapitän Koldwey / herausgegeben von dem Verein für die deutsche Nordpolfahrt in Bremen 2: 262–399. Caine EA (1986) Carapace epibionts of nesting loggerhead sea turtles: Atlantic coast of U.S.A. Journal of Experimental Marine Biology and Ecology 95(1): 15–26. https://doi. org/10.1016/0022-0981(86)90084-5 Caribbean Amphipoda of Panama (2025) Occurrence dataset. https://www.invertebase. org/portal/ident/key.php?clid=58&pid=4&dynclid=0&taxon=All+Species Catta JD (1876) Note sur quelques crustacés erratiques. Annales des Sciences naturelles, Zoologie et Paléontologie comprenant l’Anatomie, la Physiologie, la Classification et l’Histoire naturelle des Animaux 6(3): 1–33. https://archive.org/details/ essaisurquelques00catt Chevreux E (1907) Diagnoses d’amphipodes nouveaux recueillis dans les possessions de L’Océanie, par M.L. Seurat, directeur du laboratoire de recherches biologiques de Rikitea. Bulletin du Museum d’Histoire Naturelle 13(6): 412–417. https://doi. org/10.5962/bhl.part.4480 Chevreux E (1908) Description de deux nouvelles espèces d’amphipodes des parages de Monaco. Bulletin de l’Institut Océanographique 113: 1–8. https://archive.org/details/biostor-236136 Coleman CO (2003) “Digital inking”: How to make perfect line drawings on computers. Organisms, Diversity & Evolution 3(14): 1–14. https://doi.org/10.1078/1439-6092-00081 Coleman CO, Barnard JL (1991) Revision of Iphimediidae and similar families (Amphipoda: Gammaridea). Proceedings of the Biological Society of Washington 104(2): 253–268. https://biostor.org/reference/85776 Costa A (1853) Relazione sulla memoria del Dottor Achille Costa, di ricerche su’ crostacei amfipodi del regno di Napoli. Rendiconto della Societa Reale Borbonica. Accademia delle Scienze 2: 167–178. https://doi.org/10.5962/bhl.title.2070 Culpepper TJ (1969) A taxonomic and ecological study of selected benthonic and gammarid crustaceans from the northeastern Gulf of Mexico. PhD thesis, Texas A&M University, College Station, Texas. https://hdl.handle.net/1969.1/DISSERTATIONS-173931 Dana JD (1852) On the classification of the Crustacea Choristopoda or Tetradecapoda. The American Journal of Science and Arts 14(41): 297–316. https://biostor.org/reference/235591 Dana JD (1853) Crustacea. Part II. United States Exploring Expedition 14: 689–1618. https://www.sil.si.edu/DigitalCollections/usexex/navigation/ScientificText/usexex19_20a.cfm