Collembola from Hundidero-Gato Cave in Southern Spain, with the description of a new species of Entomobrya Rondani, 1861 (Collembola, Entomobryidae)

Collembola from Hundidero-Gato Cave in Southern Spain, with the description of a new species of Entomobrya Rondani, 1861 (Collembola, Entomobryidae) Javier I. Arbea1, Virginia García López2, Francisco Javier Soria2, Pedro Abellán2 1C/ Ría de Solía 3, ch 39, 39610, Astillero, Spain 2Laboratorio de Entomología Aplicada, Departamento de Zoología, Facultad de Biología. Avda. Reina Mercedes, 6, 41012, Sevilla, Spain Corresponding author: Javier I. Arbea ([email protected]) Academic editor: Ľubomír Kováč|Received 21 March 2021|Accepted 14 April 2021|Published 19 April 2021 http://zoobank.org/4B29C24B-8715-4620-88E9-B4D0086F98FB Citation: Arbea JI, López VG, Soria FJ, Abellán P (2021) Collembola from Hundidero-Gato Cave in Southern Spain, with the description of a new species of Entomobrya Rondani, 1861 (Collembola, Entomobryidae). Subterranean Biology 38: 77–90. https://doi.org/10.3897/subtbiol.38.66254 Abstract This paper deals with some Collembola from a cave at La Sierra de Grazalema (Málaga). In total, eight species of springtails were found. Two may represent new species but there is insufficient material available to prepare full descriptions (one species in the genus Ceratophysella, one in Hypogastrura), one species (Folsomides cf. ayllonensis) is identified to species, but differences from the nominal species suggest further studies may indicate the Grazalema populations represent a distinct form, and one other is described as new to science, Entomobrya virginiae Arbea, sp. nov. The new species is characterized by no sexual dimorphism in colour pattern, 5 central macrochaetae on Abd II and 4 macrochaetae on Abd III. For the identification and description of the new species, the set of characters proposed by Jordana and Baquero (2005) was used. Keywords Arthropoda, biospeleology, Entomobryidae, Entomobrya, taxonomy Introduction The Hundidero-Gato system, within the Subbaetic Mountain range (Southern Spain), is a hydrogeological system composed by more than 10 km of galleries. This cave, located between the municipalities of Montejaque and Benaoján in the province of Málaga Subterranean Biology 38: 77–90 (2021) doi: 10.3897/subtbiol.38.66254 https://subtbiol.pensoft.net Copyright Javier I. Arbea et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Subterranean Biology Published by The International Society for Subterranean Biology A peer-reviewed open-access journal Javier I. Arbea et al. / Subterranean Biology 38: 77–90 (2021) 78 (Andalusia, Spain), has two mouths: the first one is Hundidero, which acts as a sink, and the other one, which is called Gato, where the complex drains. The system harbours a wide variety of subterranean environments, including an old subterranean river course, subterranean lakes, broad chambers and galleries (Guerrero Sánchez 2015). The information about the subterranean biology in this system is scarce and fragmented (García-López et al. 2020). The first studies were carried out in 1865 by Lucas von Heyden, a German entomologist who wanted to find blind coleopterans. Subsequently, the abbot Henri Breuil, in 1914, could see the presence of warm guano inside the cave but did not capture anyone. Years later, in the 1970s, some specific surveys were carried out by certain speleological groups, such as the GE Telefónica of Madrid, GEOS of Sevilla and the E.R.E from C.E.C. from Barcelona, among others. In 1978, a Dutch speleological group described the spider Iberoneta nasewoa Deeleman-Reinhold, 1984, the aquatic amphipod Pseudoniphargus stockin Notenboom, 1987, and the gastropod Iberhoratia gatoa (Boeters, 1980) (Boeters 1980; Deeleman-Reinhold 1984; Notenboom 1987). Despite the interest of many researchers throughout decades, the deepest and most extended studies did not begin until March of 2016 (Hernando and García-López 2016), which revealed a new endemic species, the troglobitic staphylinid Phloeocharis manu Hernando & García-López, 2016. More recently, twelve spider species have been recorded for this cave, which belong to nine families: Agelenidae, Araneidae, Dysderidae, Hahniidae, Linyphiidae, Liocranidae, Segestriiadae, Tetragnathidae and Uloboridae) (Barrientos et al. 2019). There are few references on the cave-dwelling Collembola in the Subbaetic System. Only nine species have been recorded in some caves from Sierra de las Nieves, Sierra de Almijara and Sierra de Tejeda (Arbea and Baena 2003; Arbea et al. 2011; Arbea 2012): Ceratophysella engadinensis (Gisin, 1949), Deuteraphorura cebennaria (Gisin, 1956), Onychiurus gevorum Arbea, 2012, Entomobrya pazaristei Denis, 1937, Lepidocyrtus flexicollis Gisin, 1965, Pseudosinella infrequens Gisin & Gama, 1969, Pseudisotoma monochaeta (Kos, 1942), Heteromurus nitidus (Templeton, 1835) and Troglopedetes absoloni Bonet, 1931. This is the first study in which a cave from the Sierra de Grazalema have been sampled for Collembola capture. The biospeleological work has been developed in the Hundidero-Gato system. A total of 597 specimens have been captured, belonging to 8 different species. Among them there is one new species, belonging to the genus Entomobrya. Material and methods Cave description The Hundidero-Gato system is located in the northeast extreme of Sierra de Líbar, within the mountain range of Ronda, in the northwest of the province of Málaga. In this cave we can find three characteristic types of karstification: the first floor corresponds to a first stage, while the lower floor is always flooded; the middle floor is the most relevant as it corresponds with the speleological trek and it is the most developed. Collembola from Hundidero-Gato 79 Due to the extension of the system, we have limited the study area to the most accessible part at the entrance. The coordinates of Hundidero are 36°43'39"N, 5°14'19"W, about 558 m above the sea level. The entrance of the cave has a width of 10 m and a height of approximately 60 m, and 400 m of depth accessible on foot. Sampling We used baited pitfall traps to collect invertebrates, which were placed in some areas of the cave that were susceptible to harbor fauna. For the pitfall traps we used clinical analysis cans (volume 150 ml), which were buried and filled with a modification of Turquin´s liquid (Domingo-Quero and Alonso-Zarazaga 2010). The traps were baited with Majorcan sausage (cured sausage from Balearic Islands made with pork, paprika, salt and other spices) as attractant (Belda-García et al. 2014). All collected specimens were preserved in 70% ethanol. Two areas were sampled: the entrance to the cave, which covers about 400 m from the mouth to the first lake, and the area called gallery, a ledge located after about 20 m from the lake, about 20 m in the vertical of the wall, corresponding to the deepest area that was sampled. In total, sixteen pitfall traps were placed: four in semi-darkness (twilight) and four in total darkness in the entrance area; and five traps in soil with guano and three in soil without guano in gallery. The sampling was carried out in 2016 (both the entrance and gallery) and 2018 (only the entrance), and the traps were placed in the dates that the Natural Park of Sierra the Grazallema allowed us. The traps were in the cave for one week. The entry seasons established by the Park was governed by the activity of the bats, allowing us access from mid-March to mid-April and later from mid-August to mid-November, in order to not disturb the breeding and wintering periods of the bats. Preparation and analysis Some specimens were cleared in Nesbitt’s fluid and were mounted in Hoyer’s medium for compound microscope observation in phase constrast. Figures were drawn with a camera lucida. Terminology Chaetotaxy schemes in Entomobrya follow Szeptycki (1979), Jordana and Baquero (2005) and Jordana (2012). Symbols used in dorsal chaetotaxy schemes are: open circle in the figures stands for the presence of large mesochaetae or macrochaetae that could be absent in male and juvenile specimens but present in females, closed circle stands for macrochaetae that are always present, black chaetae-like drawings to sensilla, large black circles with a cross line to pseudopores, long chaetae to bothriotricha. Abbreviations used: Abd = abdominal segment; Ant = antennal segment; as = sensilla; mc = mesochaeta(e); Mc = macrochaeta(e); psp = pseudopore; Th = thoracic segment; MNCN = National Museum of Natural Sciences at Madrid, Spain; MZUN = Museum of Zoology, University of Navarra, Spain. Javier I. Arbea et al. / Subterranean Biology 38: 77–90 (2021) 80 Results Family Hypogastruridae Börner, 1906 Ceratophysella sp. Material studied. Cueva del Gato, twilight zone, 27-III-2016, 1 ♀ The single individual collected apparently represents an undescribed species similar to C. norensis Cassagnau, 1965, characterized by A-type of chaetotaxy (p1 chaeta shorter than p2 chaeta on Abd IV), dens with 6 chaetae, the basal chaeta more than twice as long as the others, retinaculum with 4+4 teeth, tibiotarsi with one pointed tenent hair, claw with one internal tooth and two lateral teeth, filament of empodium 2/3 as long as the inner edge of claw, Ant IV with trilobed apical bulb and 7 thin sensilla, slender anal spines 1.5 times the long of the claws and 1.8 mm length. The species is dark blue and does not show characters typically present in cave-adapted species. Additional material is needed to confirm the identity of the species. Hypogastrura sp. Material studied. Cueva del Gato, twilight zone, 27-III-2016, 1 juv. The single individual collected appears to represent a new species similar to H.vernalis (Carl, 1901), characterized by tibiotarsi with one slightly knobbed tenent hair, empodium with broad basal lamella, dorso-lateral parts of Th II–III with m6 chaeta, Ant IV with trilobed apical bulb and 7 sensillae, dens with 6–7 chaetae, 2.7 times as long as mucro, PAO nearly the same size as an ommatidium, anal spines minute, on high papillae, coarse body granulation (8 granules between the p1 chaetae of Abd V) and 1 mm length. The species is grey-blue and does not show characters typically present in cave adapted species. Additional material is needed to confirm the identity of the species. Mesogastrura ojcoviensis (Stach, 1919) New Sierra de Grazalema (Málaga) record. Material studied. Cueva del Gato, twilight zone, 27-III-2016, 16 ex; dark zone, 14IV-2016, 1 ex, 13-XI-2016, 2 ex, 4-X-2018, 25 ex; cave galleries, 14-IV-2016, 1 ex, 30-IX-2016, 1 ex. Edaphic and troglophilous, guanophilous species. This is a common European species in the caves of the Iberian Peninsula (Spain and Portugal) and the Balearic Islands (Jordana et al. 1997). Collembola from Hundidero-Gato 81 Figure 1. Topography of Hundidero-Gato system and locations where the Collembola were sampled. Modified from Guerrero Sánchez (2015). In brown, the twilight pitfall traps, in blue, the darkness pitfall traps and in red, gallery traps (five on guano and three on ground without guano). The different species that appear in each area are represented with their own symbol in the legend. Xenylla maritima Tullberg, 1869 New Sierra de Grazalema (Málaga) record. Material studied. Cueva del Gato, twilight zone, 27-III-2016, 3 ex, 16-VIII-2018, 1 ex. This is a cosmopolitan species known to occur in dry habitats, surface leaf litter or lichens on rocks (Thibaud et al. 2004). May appear in the mesovoid shallow substratum or in caves accidentally. Family Isotomidae Schäffer, 1896 Folsomides cf. ayllonensis Simón & Luciáñez, 1990 New Sierra de Grazalema (Málaga) record. Material studied. Cueva del Gato, dark zone, 30-IX-2016, 1 ex. The species lacks pigment, but has 5+5 eyes. The juvenile (0.5 mm) examined differ from F. ayllonensis, as original description (Simón and Luciáñez 1990) and notes made by Fjellberg (1993), in having an oval postantennal organ, 1.7–1.8 as long as omma (>2 in F. ayllonensis), and in having three posterior chaetae on dens (two in F. ayllonensis). Javier I. Arbea et al. / Subterranean Biology 38: 77–90 (2021) 82 Figure 2. Hundidero Gato cave a exterior view from Hundidero b Hundidero entrance c, d dark zone, making direct captures (Photo by Miguel de Felipe). The physical distance (≈690 km) and morphological differences between the Grazalema and Ayllón populations suggest they may represent distinct species, but additional material from Sierra de Grazalema will be needed to determine if the morphological differences noted here are fixed. Collembola from Hundidero-Gato 83 Family Entomobryidae Schäffer, 1896 Entomobrya virginiae Arbea, sp. nov. http://zoobank.org/0391BA36-456A-44BE-84BA-5C82C944D00A Figs 3–15, Tables 1, 2 Type locality. Sistema Hundidero-Gato, Benaoján-Montejaque, Málaga (Sierra de Grazalema Natural Park, Spain), 36°43'39"N, 5°14'19"W, 558 m a.s.l. Type material. Holotype female on slide, Sistema Hundidero-Gato, BenaojánMontejaque, Málaga (Spain), dark zone, 23-VIII-2018, leg. Virginia García López; 80 paratypes, same data as holotype: 12 females, 4 males and 4 juveniles on slide (11 from twilight and 9 from dark zone) and 60 ex. in a tube with ethyl alcohol (20 from twilight and 40 from dark zone). Deposited in MNCN (holotype and paratypes in slides) and MZUN (paratypes in alcohol). Etymology. The name is dedicated to Virginia García López, who captured the specimens. Description. Body length 1.80 mm, excluding antennae (mean 16 ex., Table 1). Without dimorphism in colour; ground colour white or very light blue, with blue pigment on lateral body (all segments), dorsolateral segments Th II to Abd V, as two not complete stripes wider on posterior tergites, a central patch on Abd III with a truncated cone shape, other central patches on Abd I–II, and transversal bands on posterior tergites Th II–Abd III in many specimens; head with pigment on posterior lateral eyes and a dorsal V-shaped patch; on legs, pigment on distal femur and lateral tibiotarsus; antennae with pigment on Ant I tip and whole Ant II–IV (Fig. 3). Simplified Mc formula (Jordana and Baquero 2005) H1-H2-H3-H4-H5/T1-T2/A1-A2/A3-A4-A5/ A6-A7-A8-A9-A10 in adult females: 3-2-0-3-2/2-4/2-3/1-2-1/0-4-3-2-2. Head. Eight eyes, GH smaller than EF. Antennae length 1.08 mm, 3.13 times the length of the head (n = 16, Table 1); Ant IV with apical vesicle simple (Fig. 10) (slightly bilobed in some specimens); relative length of Ant I/II/III/IV = 1/2.38/2.42/2.43 (Table 1). Labrum with 4/5,5,4 chaetae; prelabral chaetae ciliated, and labral chaetae smooth. The labium has MR*ELL ciliated Mc; R* half as long as M; the remaining labial Mc are smooth. The maxillary palp has three sublobal chaetae. The papilla E has a lateral process reaching the end of the papilla (Fig. 9). In the dorsal head chaetotaxy (Fig. 4), the H1 area has three Mc: An2, An3e1 and An3, and the H2 area with two Mc: A5 and A6 (sometimes absent or as mc in male and juvenile specimens); Mc series M with M1–M4; the H3 area without Mc S’0; the H4 area with S1, S3 and S4 Mc, and the H5 area with Ps2 and Ps5 Mc. There are four chaetae on the ocular well: p, q, r and s. Thorax (Fig. 5). Th II has two Mc: m1 and m2i, on the T1 area; the T2 area has four Mc: m4, m4i, a5 and a5’ (sometimes absent or as mc in male of juvenile specimens). Th III has complete basal chaetotaxy: a1–a7, p1–p6, m6–m7. Abdomen (Figs 6, 7). The Abd II has two Mc on area A1: a2 and a3 (sometimes absent or as mc in male or juvenile specimens) and three Mc on area A2: m3, m3ep and m3e. Abd. III has 1, 2 and 1 Mc on areas A3, A4 and A5, respectively: a1, a2, a3 (some- Javier I. Arbea et al. / Subterranean Biology 38: 77–90 (2021) 84 Figure 3. Entomobrya virginiae Arbea, sp. nov. Habitus. Figures 4–7. Entomobrya virginiae Arbea, sp. nov. 4 head chaetotaxy 5 Th II chaetotaxy 6 Abd II–III chaetotaxy 7 Abd IV chaetotaxy. Symbols: open circle = Mc that could be absent in male and juvenile specimens but present in females; closed circle = Mc that are always present; black chaetae-like = sensilla; black circles with a cross line = pseudopores; long chaetae = bothriotricha. times absent or as mc in male or juvenile specimens) and m3. Abd. IV with 11+11 central Mc: A3–A6, B3–B6, C1 (sometimes absent), C2a and E1 (Fig. 7). The trichobothria on Abd IV at the levels T2 and T4. Length ratio of Abd IV/III = 3.78 (n=16, Table 1). Length of manubrium and dens 0.35 and 0.43 mm, respectively (n=16, Table 1). Manubrial plate with four chaetae and two pseudopores (Fig.13). Mucro with teeth similar in size, mucronal spine reaching tip of subapical tooth (Fig.12). Collembola from Hundidero-Gato 85 Figures 8–15. Entomobrya virginiae Arbea, sp. nov. 8 labrum 9 labial papilla E 10 tip of Ant IV 11labral papillae 12 tip of dens and mucro 13 manubrial plate (open circles = Mc; gray circles = pseudopores) 14trochanteral organ 15 claw and empodium of leg III; Scale bars: 0.02 mm (8, 12–15), 0.01 mm (9–11). Legs. Trochanteral organ with 15–16 smooth chaetae in V-shaped and 7–8 lateral smooth chaetae (Fig. 14). Tibiotarsus not subsegmented, without smooth chaetae, except for smooth terminal chaeta on legs III. Claw with four inner teeth: paired at 53–58% (one of them larger and forward), first unpaired at 70% from basis, and the last one closer than 90%; dorsal teeth at the level of lateral teeth (Fig. 15). Empodium lanceolate, with serrated external lamella in leg III. Tenent hair clavate, longer than claw. Remarks. For the identification of the species of Entomobrya we must consider a combination of colour pattern and dorsal macrochaetotaxy. It has been shown that species with the same colour pattern can have a different chaetotaxy (Jordana and Baquero 2005). On the other hand, species with differences in color pattern can correspond with species-level genetic divergence without any obvious differences in chaetotaxy (Katz et al. 2015b).If the macrochaetotaxy of Th II/Abd II/Abd III is considered simultaneously, twelve species of the genus share a similar simplified formula for these tergites: 2-3/2-3/1-2-1 in E. atrocincta Schött, 1896, E. maroccana Baquero & Jordana, 2008, E. melitensis Stach, 1963, E. numidica Baquero, Hamra-Kroua & Jordana, 2009, E. vergarensis Baquero, Arbea & Jordana,