Two new troglobiont Pygmarrhopalites species of the principalis group (Collembola: Arrhopalitidae) from the West Caucasus Author Vargovitsh, Robert S. text Zootaxa 2017 4250 1 23 42 journal article 33319 10.11646/zootaxa.4250.1.2 1c5bce12-4b99-4480-a230-9fe3cd5e0fee 1175-5326 439780 CDE1CCE1-71E1-4947-A7BE-9C9F98B26C81 Pygmarrhopalites dbari sp. nov. Figs 2–33 , Tables 1 –3 Diagnosis. Body up to 1.1 mm length with elongated appendages ( Fig. 2 ). Eyes 1 + 1. Trichobothria ABC form an angle 150–160o and AB<BC. Antenna about 3× of the head, Ant IV with 7 distinctly separated subsegments and 13 whorls of setae. Head dorsum with 5 + 1 + 5 weakly spine-like setae. Femur II with 13 and III with 12 setae. All claws slender, without tunica and with inner tooth. Tips of empodia not reaching tips of corresponding claws, empodium I–II with and III without corner tooth. Manubrium with 7 + 7 posterior setae; dens with 2 outer and 1 inner spine-like setae. Tip of mucro rounded, slightly broadened. Abd VI with broadened circumanal setae and palmate appendices anales with secondary branching. Type material . Holotype : female, dissected and mounted on four slides (C-801a-2a: head, C-801a-2b: furca, C-801a-2c: Abd VI , C-801a-2d: great abdomen with legs), West Caucasus , Abkhazia , Novy Afon , valley of the Psyrtskha River , Psyrtskha Cave , 25.viii.2011 , R.S. Vargovitsh leg. Paratypes on slides: 4 males, 2 females and 3 juv. collected together with holotype; same cave and collector, 17.vi.2006 , 2 males, 1 female, 1 juv. Description. Female. Total length without appendages up to 1.1 mm . Pigmentation absent in young specimens and present in adults as reddish spots, more intensive on the dorsum of head and thorax ( Fig. 25 ). Head ( Figs 3 , 28 ). Eyes 1 + 1, about 8 µm in diameter, reddish or unpigmented. Clypeal area: row a : 4 + axial + 4 setae, rows b , c and e with 5 + 5 setae each, row d with 7 + 7 setae, row f with 6 + 6 setae, median region M with 2 asymmetrically arranged setae (marked with oval in Fig. 3 ). Interantennal area: row α : 2 + 2, row β : 1 + axial + 1. Dorsal area (rows A to D ): axial seta present in rows A , B and C ; weakly spine-like setae ( Fig. 11 ) in rows B (1 + 1), C (2 + 1 + 2) and D (2 + 2). Chaetotaxy of the head posterior side as in Fig. 3 (dotted lines). Chaetotaxy of mouth region. Labrum ( Fig. 3 ): labral / prelabral chaetotaxy: 4 5 5 / 6. Labium: submentum with 4 setae, mentum with 5 setae; labial palp ( Fig. 4 ) with 5 proximal setae, 5 papillae ( A , B , C , D , E ) with deeply inserted setae and with 11 associated guard setae (hooked a1 , b1-4 , d1-3 , e1-3 ) and 3 hypostomal setae ( H , h1 , h2 ). Maxilla: apical seta of the maxillary outer lobe ( Fig. 5 ) with short and thin subparallel branch at the base, sublobal plate with three sublobal hairs. Oral fold with 2 setae. Antenna ( Figs 6–7 ) as long as body (~ 1 mm ) and about 3× of head. Length ratio of antennal segments I: II: III: IV = 1: 3.1: 5.2: 14.1; basal subsegment of Ant IV subequal with Ant III. Ant I with 7 setae, p as microseta. Ant II with 15 setae, two interior ones about twice longer than others. Ant III with 18 setae and 2 scabrous (not smooth) and relatively long (9–10 µm) sense rods in separate pits ( Fig. 26 ); antennal III organ as in figs 6 and 26. Ant IV ( Fig. 7 ) bears 13 whorls of setae located in 7 distinct subsegments; subsegmental formula: 1 + 5 + 1 = ( A1–A3 + M1 ) + ( M2–M6 ) + ( BA + BM1–BM2 + BB ). 1–2 small intercalar pseudosubsegments without setae present between normal subsegments. Apical subsegment with knobbed subapical organite and short blunt apical sensillum A 1p . Foreleg ( Figs 8 , 20 , 27 a): precoxae 1, 2 and coxa with 1, 0, 1 setae respectively ( Fig. 20 ). Trochanter with 3 anterior and 1 posterior setae. Femur with 14 setae, a4 turned perpendicularly to the longitudinal axis of the segment, p1 and p3 thin and short. Tibiotarsus with 45 setae: whorl I with 9 setae among which Ja curved and somewhat thickened, each of whorls II–V with 8 setae and region F with 3 primary FP setae ( e , ae , pe ) and secondary seta FSa . Pretarsus with 1 anterior and 1 posterior setulae. Foot complex ( Fig. 27 a): claw thin, without tunica, with inner tooth and two pairs of indistinct lateral teeth, about 5.8× shorter than tibiotarsus; empodium about 1.7× shorter than claw, thin, with corner tooth, with short apical filament not reaching the tip of claw. Mid leg ( Figs 9 , 20 , 27 b): precoxae 1 and 2 with 1, 1 setae respectively, precoxal process present, coxa with 3 setae and microsensillum ( Fig. 20 ). Trochanter with 5 setae: 3 simple anterior, trochanteral organ and 1simple posterior. Femur with 13 setae ( pe2 and ae3 absent), p1 and p3 very thin. Tibiotarsus with 44 setae: whorl I with 9 setae whorls II–IV with 8 setae, whorl V with 7 setae ( Vp absent), region F with 3 FP setae and FSa seta. Foot complex ( Fig. 27 b): claw thin, without tunica, with inner tooth, with 2 pairs of small lateral teeth, about 6× shorter than tibiotarsus; empodium somewhat broader and distinctly shorter than in foreleg, with corner tooth, about 2.2× shorter than claw. Hind leg ( Figs 10 , 20 , 27 c): precoxae 1 and 2 with 1, 1 setae respectively, process on precoxa 1 present, coxa with 3 setae and microsensillum ( Fig. 20 ). Trochanter chaetotaxy as in midleg. Femur with 12 setae ( pe2 and ae3 absent), p1 and p3 as microsetae. Tibiotarsus with 44 setae as in mid leg. Foot complex ( Fig. 27 c): claw relatively slender, without tunica, with inner tooth, with 2 pairs of small lateral teeth, about 8× shorter than tibiotarsus; empodium about 1.6× shorter than claw, broad, without corner tooth, with short apical filament not reaching the tip of corresponding claw. Lengths ratio of tibiotarsi I: II: III = 1: 1: 1.2. Tibiotarsus I about 1.2× shorter than head. Ventral tube ( Fig. 20 ) with 1 + 1 subapical setulae. Tenaculum ( Fig. 22 ): with 2 apical setulae on the anterior lobe, 3 teeth and a basal process on each ramus. Furca ( Fig. 21 ): manubrium with 7 + 7 posterior setae. Dens (23 setae): anterior side with 3, 2, 1, 1 setae; posterior side with Ipe and IIpe as massive spines ( Figs 14, 15 ), Ii moderately spine-like, IIIpi and IVpi not spinelike. Mucro ( Fig. 30 ): posterior lamellae serrated (about 25–30 teeth), anterior lamella poorly developed; tip rounded and somewhat broadened. Dens about 1.8× as long as mucro. Great abdomen ( Fig. 20 ): Th II bears single sensillum in row a and 3 setae in row m with m1 somewhat spinelike and longer than other setae of Th II ( Fig. 12 ). Th III with sensillum in row a and 3 setae in row m . Abd I bears single row with 5 short setae ( Fig. 13 ). Abd II with row of 4 setae anterior to trichobothrial complex. Trichobothrial complex ( Fig. 29 ): ABC form an angle about 160° (157–161°) and AB is ~0.8× of BC . Seta p is located below the level of trichobothrium B ; seta b1 lies almost in the middle of line BC ; seta c1 (~27 µm) somewhat shorter than c2 but not reduced. Posterior lateral complex with 6 and furca base complex with 9 setae. Central dorsal complex with three setae of which seta 3 is shorter and thinner than 1 and 2 ( Fig. 20 ). Posterior dorsal complex with about 18 setae the longest of which ( dI-1 ~100 µm) is 2–2.4× longer than hind claw ( Fig. 16 ). Ventral complex with up to 3 setae. Fifth abdominal segment ( Fig. 20 ): with 2 setae and trichobothrium D in row a , and 2 setae in row p ; seta a3 thinner and somewhat shorter than others. Genital field with 2 + 2 short setae. Sixth abdominal segment ( Figs 23 , 33 ): dorsal valve with 11 + 2 axial + 11 setae, of which circumanal setae ms1 ( Fig. 17 ), mps1 , mps2 and mps3 ( Figs 18 , 33 ) are moderately broadened. Each of lateral valve bears 20 setae with broadened mpi1 and mpi2 ( Fig. 33 ). Some of circumanal setae (e.g. mps3 , mpi2 ) slightly serrated near bases. Appendices anales ( Figs 19 , 33 ) palmate and broadened in distal third, with secondary branches present (length about 27 µm and width of the palmated part about 15 µm in dorsoventral position). In total, normally 64 setae on Abd VI are present ( Fig. 23 ). Male. Habitus as in Fig. 2 . Body length about 0.8 mm , measurements are given in Table 1 , chaetotaxy resembles the one in female, except for small abdomen. Ant IV has a stronger tendency than females to separate terminal part of subsegments and thus bears up to 5 short naked intercalar pseudosubsegments between normal subsegments ( Fig. 31 ). Besides, the basal subsegment is often secondarily subdivided into up to 5 pseudosubsegments by several annuli between them ( Fig. 31 ). Abd VI ( Figs 24 , 32 ) without broadened setae, with 7 + 2 + 7 setae on dorsal valve and 14 + 14 setae on lateral valves: 44 in total. Genital opening is surrounded with about 14 short setulae. TABLE 1 . Measurements (in µm) for body parts of types of Pygmarrhopalites dbari sp. nov. and P. kovali sp. nov. Body part dbari kovali Females, n= 4 Males , n= 6 Females , n= 3 Males , n=2 min–max mean min–max mean min–max mean min–max mean Total 1000–1088 1065 772–880 831 920–960 937 830–? 830 Variability. A number of short naked intercalar pseudosubsegments on Ant IV varies: in females from 1 (usually) to 2, in males from 2 to 5 (most often 4). Secondary pseudosubsegments of the Ant IV basal subsegment usual in males and vary from 2 to 5. Among 14 examined specimens, in one female, a small corner tooth was observed on one empodim III. Ventral complex of great abdomen with 3 or 2 setae.

Body	670–740	717	512–640	584	610–677	636	580–?	580
Head	345–368	357	265–300	280	310–360	336	296–307	302
Head longest spine	23–35	29	22–27	23	24–26	25	22–23	22
Eye diameter	7.0–9.0	8.0	6.0–6.7	6.4	9.3–10.4	9.8	9.2–9.3	9.3
Antenna	98 9–1033	1017	837–856	850	740–777	756	693–745	719
Ant I	42–47	45	36–38	37	42–45	44	36–37	37
Ant II	13 6–140	137	103–124	109	101–105	102	95–100	98
Ant III	21 2–243	234	174–200	188	160–176	167	136–162	149
Ant IV	61 6–650	631	522–545	530	444–463	451	434–445	440
Ant IV basal subs.	220–240	235	180–208	196	199–210	203	194–203	199
Ant III organ rods	8.0–10.0	9.3	9.0–9.5	9.3	4.4–4.5	4.5	3.9–4.3	4.1
Tita I	280–306	292	225–241	232	244–259	250	238–238	238
Tita II	280–305	293	225–237	232	240–262	249	245–245	245
Tita III	346–368	355	275–295	285	278–313	296	288–290	289
Claw I	49–51	50	37–42	40	52–55	54	48–50	49
Claw II	48–49	49	36–41	38	50–55	52	48–49	48
Claw III	44–46	45	36–39	37	49–54	52	46–46	46
Emp I	28–31	30	18–24	22	29–35	31	25–31	28
Emp II	20–24	23	15–18	16	27–28	28	25–25	25
Emp III	27–29	28	19–24	22	29–30	29	26–28	27
Abd dI-1	90–104	97	80–84	82	70–85	76	81–?	81?
Abd VI longest seta	63–65	64	41–47	43	62–69	66	40–40	40
App an, length	26–27	27	-	-	28–35	31	-	-
App an, max. width	14–15	15	-	-	15–17	16	-	-
Manubrium	209–222	214	155–171	162	207–226	217	194–197	196
Dens	231–250	242	181–204	193	212–236	221	205–218	212
Mucro	133–138	136	110–122	116	130–149	137	128–130	129

FIGURES 1–2. 1, type localities of Pygmarrhopalites dbari sp. nov. ( 1 —Psyrtskha Cave), and P. kovali sp. nov . ( 2 — Tsebeldinskaya Cave, 3 —Tshalintshur Cave, 4 —Verkhnyaya Shakuranskaya Cave); 2, habitus of mounted male. FIGURES 3–7. Pygmarrhopalites dbari sp. nov. : 3, chaetotaxy of head; 4, chaetotaxy of labial palp; 5, maxillary outer lobe; 6, chaetotaxy of antennal segments I–III; 7, chaetotaxy of antennal segment IV. FIGURES 8–19. Pygmarrhopalites dbari sp. nov. : 8, chaetotaxy of foreleg; 9, chaetotaxy of mid leg; 10, chaetotaxy of hind leg; 11–19, shape of setae: 11, spine-like seta of head vertex; 12, m1 of mesothorax; 13, dorsal sea of Abd I; 14, Ie of dens; 15, IIpe of dens; 16, dI-1 of great abdomen; 17, ms1 of Abd VI; 18, mps3 of abd VI; 19, appendices anales. FIGURES 20–24. Pygmarrhopalites dbari sp. nov. : 20, chaetotaxy of great abdomen, red arrow directed downward points out a position of seta p below the level of trichobothrium B; 21, chaetotaxy of furca; 22, tenaculum; 23, chaetotaxy of female Abd VI; 24, chaetotaxy of male Abd VI. FIGURES 25–30. Pygmarrhopalites dbari sp. nov. : 25, habitus of alcohol specimen; 26, chaetotaxy of antennal III organ; 27, foot complex (a—fore, b—mid, c—hind); 28, fragment of head dorsum; 29, chaetotaxy of trichobothrial complex; 30, mucro and distal part of dens. FIGURES 31–33. Pygmarrhopalites dbari sp. nov. : 31, Ant IV of male; 32, small abdomen of male, lateral view; 33, fragment of female Abd VI with circumanal setae, posterior view. Bionomy and distribution. P. dbari sp. nov. lives in the distant aphotic zone of the cave with air temperature 13.0°C and water temperature 12.6°C. Not numerous specimens were collected on the water surface of the siphon and nearby in 2006 and 2011 but were missing in September 2015 . They occur together with two Pygmarrhopalites species from pygmaeus -group and Arrhopalites abchasicus . Thus, relatively small Psyrtskha Cave is inhabited by four sympatric species of the family. Unlike A. abchasicus , P. dbari was not found in neighbour and hydrologically connected huge Novoafonskaya Cave. Due to its morphology (much elongated antennae, well-developed antennal organ, thin claws with short empodia, poor or absent pigmentation) and topical preferences, this species can be classified as a highly troglomorphic troglobiont. Conservation status. The new species demonstrates extremely restricted distribution and is confined to the only cave: no findings in other nearby caves of Novy Afon as well as in numerous W Caucasian caves of other karst massifs and also in epigean environment were registered. Troglomorphic appearance confirms that the species is ecologically specialized cave/subterranean inhabitant. Number of individuals of this species in Psyrtskha Cave, located in active touristic zone, is visually much lower than of cohabiting Arrhopalites abchasicus and two other representatives of Arrhopalitidae . According to IUCN (2012) classification P. dbari sp. nov. most credible corresponds to the category Vulnerable and criterion D2 : “Restricted area of occupancy or number of locations with a plausible future threat that could drive the taxon to Critically Endangered or even Extinct in a very short time”. Therefore, P. dbari sp. nov. should be included into IUCN Red List of Threatened Species and meet adequate protection of its habitat—Psyrtskha Cave. Etymology. The new species is dedicated to Dr. Roman Dbar (Sukhum) for his great contribution to study and protection of Abkhazian nature, including amazing Novoafonskaya Cave. Remarks. Among about 30 described species of the principalis group with palmated appendices anales, Nearctic P. arca ( Zeppelini & Christiansen, 2003 ) , P. bellingeri ( Christiansen, 1966 ) , P. hubbardi ( Zeppelini & Christiansen, 2003 ) and Japanese P. octacanthus ( Yosii, 1970 ) , as well as new species, normally bear 7 subsegments on Ant IV. Among them and within principalis group only P. arca shares with the new species muchelongated antennae, 3× of head. Differential characters for species with 7 subsegments on Ant IV are given in Table 2 . Additionally, it is notable that the number of setae on femur II (13 setae) and III (12 setae) in P. dbari sp. nov. is less than in other representatives of the principalis group for which this character is known to date ( P. pseudoprincipalis , P. principalis skelicus , and P. kovali sp. nov. described below). TABLE 2. Differences between Pygmarrhopalites dbari sp. nov. and congeners of principalis group with 7 subsegments on Ant IV.

Character / Species	dbari sp. nov.	arca	bellingeri	hubbardi	octacanthus
Ant/head	3	2.7-3	?	2	1.7
Axial setae of head dorsum	4	4	4	5	5
Seta ms1 of Abd VI	not forked	forked	not forked	forked	not forked
Claw tooth I, II, III	+ + +	— + +	+ + +	+ + +	— + +
Emp tooth I, II, III	+ + —	+ + +	+ + +	+ + +	— — —
Emp tip: claw tip I, II, III	<<<	>> =	> = =	> = =	>>> (> = =)
Basal papilla on Ant III	—	—	—	+	+
eyes per side	1	1	2	1+1 vestigial	1
spiny setae on dens	3	5	5	5	6
spiny setae on head	5+1+5 weak	—	+	—	4+4 heavy
Pygmarrhopalites kovali Figs 34–61, Tables 1, 3	sp. nov.

Diagnosis. Body up to 1 mm length. Eyes 1 + 1. Trichobothria ABC form a very obtuse angle and AB<BC. Antenna about 2.3× of head, Ant IV with 5 distinctly separated subsegments and 13 whorls of setae. Head dorsum with 4 + 4 moderately spine-like setae. Femur II with 15 and III with 14 setae. All claws slender, without tunica and with inner tooth. Tips of empodia not reaching tips of corresponding claws, empodium I–II with and III without corner tooth. Manubrium with 7 + 7 posterior setae; dens with 2 strongly spine-like outer and 3 moderately spinelike inner setae. Tip of mucro rounded. Abd VI with broadened circumanal setae and palmate appendices anales with secondary branching. Type material. Holotype on slide C-689-1 ( Fig. 57 ): female, the West Caucasus , Abkhazia , Gulripsh District , Tsebelda Vill., 510 m a.s.l. , Tsebeldinskaya Cave, 19.viii.2009 , R.S. Vargovitsh leg . Paratypes on slides: 2 males (one of them dissected and mounted on 4 slides) and 2 females collected together with holotype. Other material. On slides: male and 5 females , the W Caucasus , Abkhazia , Gulripsh District , vicinity of Amtkel Vill., 280 m a.s.l. , Verkhnyaya Shakuranskaya Cave, surface of Barber’s traps exposed during 18.viii.2010 – 20.viii.2011 , 70 m from entrance, R.S. Vargovitsh and A.G. Koval leg.; female, the W Caucasus , Abkhazia , Gulripsh District , vicinity of Amtkel Vill., 300 m a.s.l. , Tshalintshur Cave, surface of Barber’s traps exposed during 20.viii.2010 – 21.viii.2011 , R.S. Vargovitsh and A.G. Koval leg. Description. Female. Body length without appendages up to 1 mm , habitus of holotype in Fig. 57 . Pigmentation of alcohol specimens varies from absence to presence of reddish spots of pigment on head dorsum and interantennal area only. Head ( Figs 34 , 58 ). Eyes 1 + 1, in alcohol as very small dark pigmented spots or unpigmented. Clypeal area (rows a to f ) with axial seta in row a and median region M (marked with oval in Fig. 34 ) with two asymmetrically arranged setae. Interantennal area (rows α and β ) with axial seta in row β . Dorsal area (rows A to D ): axial setae present in rows A , B and C ; 4 + 4 moderately spine-like setae in rows C (2 + 2) and D (2 + 2). Chaetotaxy of the head posterior side as in Fig. 34 (dotted lines). Labral / prelabral chaetotaxy: 4 5 5 / 6. Maxillary outer lobe as in P. dbari ( Fig. 5 ): apical seta with short and thin subparallel branch at the base, sublobal plate with three sublobal hairs. Antenna ( Fig. 35 ): length 2.2–2.4× of head. Length ratio of antennal segments I: II: III: IV = 1: 2.2: 3.6: 9.9; basal subsegment of Ant IV 1.2 times longer than Ant III. Ant I with 7 setae of which subapical one is microseta. Ant II with 15 setae. Ant III with 18 setae and 2 relatively short (4.5 µm) sense rods in separate pits. Ant IV bears 13 whorls of setae located in 5 distinct subsegments; subsegmental formula: 1 + 3 + 1 = ( A1–A3 + M1– M2 ) + ( M3–M5 ) + ( BA + BM1–BM3 + BB ). Foreleg ( Figs 49 , 52 ): precoxae 1, 2 and coxa with 1, 0, 1 setae respectively. Trochanter with 3 anterior and 1 posterior setae; femur with 14 setae, a4 turned perpendicularly to the longitudinal axis of the segment. Tibiotarsus with 45 setae: whorl I with 9 setae among which Ja somewhat curved and thickened, each of whorls II–V with 8 setae and region F with 3 primary FP setae ( e , ae , pe ) and secondary seta FSa . Pretarsus with 1 anterior and 1 posterior setulae. Foot complex: claw thin, without tunica, with inner tooth and two pairs of indistinct lateral teeth, 4.5–4.8× shorter than tibiotarsus; empodium thin, with corner tooth, about 1.8× shorter than claw, tip of empodial filament not reaching the tip of claw. Mid leg ( Figs 50 , 52 ): precoxae 1 and 2 with 1, 1 setae respectively, precoxal process present, coxa with 3 setae and microsensillum. Trochanter with 5 setae: 3 simple anterior, trochanteral organ and 1 simple posterior. Femur with 15 setae. Tibiotarsus with 44 setae: whorl I with 9 setae whorls II–IV with 8 setae, whorl V with 7 setae ( Vp absent), region F with 3 FP setae and FSa seta. Foot complex: claw thin, without tunica, with inner tooth, with 2 pairs of small and indistinct lateral teeth, 4.7–4.8× shorter than tibiotarsus; empodium somewhat broader than in foreleg, with corner tooth, with very short apical filament not reaching the tip of corresponding claw, and about 1.9× shorter than claw. Hind leg ( Figs 51 , 52 ): precoxae 1 and 2 with 1, 1 setae respectively, process on precoxa 1 present, coxa with 3 setae and microsensillum. Trochanter with anterior trochanteral organ, 3 anterior and 1 posterior simple setae. Femur with 14 setae, among them 2 posterior microsetae. Tibiotarsus with 44 setae as in mid leg. Foot complex: claw relatively slender, without tunica, with inner tooth, with 2 pairs of small and indistinct subbasal and subapical lateral teeth, 5.5–5.7× shorter than tibiotarsus; empodium broad, without corner tooth, with short apical filament not reaching the tip of corresponding claw, and about 1.8× shorter than claw. Lengths ratio of tibiotarsi I: II: III = 1: 1: 1.2. Tibiotarsus I is about 1.3× shorter than head. Ventral tube ( Fig. 52 ) with 1 + 1 subapical setulae. Tenaculum ( Fig. 54 ): with 2 apical setulae on the anterior lobe, 3 teeth and a basal process on each ramus. Furca ( Fig. 53 ): manubrium with 7 + 7 posterior setae. Dens (23 setae): anterior side with 3, 2, 1, 1 setae; posterior side with Ie ( Fig. 39 ) and IIpe ( Fig. 40 ) as massive spines, Ii , IIIpi ( Figs 41, 42 ) and IVpi — moderately spine-like. Mucro: posterior lamellae serrated, tip rounded. Dens 1.6× as long as mucro. Great abdomen ( Fig. 52 ): Th II bears single sensillum in row a and 3 setae in row m with m1 shaped similarly to posterior cephalic spine-like setae and longer than other setae of Th II ( Fig. 37 ). Th III with sensillum in row a and 3 simple short setae in row m ( Fig. 38 ). Abd I bears single row with 5 short setae. Abd II with row of 4 setae anterior to trichobothrial complex. Trichobothrial complex usual for the genus ( Fig. 59 ): ABC form very obtuse angle (150°–170°) and AB is about 0.7× of BC ; p seta is located below the level of trichobothrium B ; seta b1 lies almost on line BC , somewhat closer to C ; setae c1 and c2 located below the level of trichobothrium C and c1 is higher than c2 . Posterior lateral complex with 6 setae. Furca base complex with 9 setae. Central dorsal complex with 3 subequal setae. Posterior dorsal complex with 22–23 setae the longest of which ( dI-1 = 72 µm in holotype ) is 1.3–1.7× longer than hind claw ( Fig. 44 ). Ventral complex with 1 or 2 setae. Fifth abdominal segment ( Fig. 52 ) with 2 thin setae and trichobothrium D in row a , and 2 thicker setae in row p . Genital field with 2 + 2 setae. Sixth abdominal segment ( Figs 56 , 60 ): dorsal valve with 11 + 2 axial + 11 setae, of which circumanal setae ms1 ( Fig. 45 ), mps1 , mps2 and mps3 ( Fig. 46 ) are distinctly broadened. Each of lateral valve bears 18 setae with broadened mpi1 and mpi2 ( Fig. 47 ). Some of circumanal setae (e.g. mps3 , mpi1 , mpi2 ) slightly serrated near bases ( Fig. 47 ). Appendices anales ( Figs 48 , 61 ) palmate and broadened in distal third, with secondary branches present (length about 30 µm and width of the palmate part about 17 µm in dorsoventral position). In total, 60 setae are present on Abd VI. Male. The length of body parts is slightly lesser than in female ( Table 1 ). Chaetotaxy resembles the one in female, except for small abdomen ( Fig. 55 ). Chaetotaxy of Abd VI differs from females by shape (no broadened setae), and number (44 setae = 7 + 2 axial + 7 on dorsal valve and 14 + 14 on lateral valves). The genital opening is surrounded by about 16 setulae. Unlike in examined females, ventral complex of great abdomen bears 3 setae, but this character is rather variable and cannot be recognized as representing sexual dimorphism. Length ratio of antennal segments I: II: III: IV = 1: 2.6: 3.7: 11.7. Ant IV bears 5 well-separated subsegments (as in female) but along with this, the basal subsegment is subdivided into 5 (pseudo)subsegments separated from each other by up to 4 more or less developed annuli. Thus, every setal whorl of basal subsegment is allocated in the separate pseudosubsegment. Tip of mucro is somewhat spoon-like, whereas in females it is rounded but rather not broadened. Chaetotaxy of small abdomen and arrangement of Ant IV subsegmentation should be considered as characters of sexual dimorphism. Variability. In one female appendices anales are deeply split into two main branches and each of them is palmate. Chaetotaxy of ventral complex of great abdomen varies. Bionomy and distribution. P. kovali sp. nov. inhabits the aphotic zone of Tsebeldinskaya Cave with air temperature 11.2–13.2°C (min-max annual) and water temperature 12.0–12.3°C. Specimens were taken from the wooden debris and from the water surface. In this cave, the new species cohabits with three other Arrhopalitidae species from the genera Pygmarrhopalites and Troglopalites . Due to its morphology (elongated antennae, thin claws with short empodia, poor or absent pigmentation) and topical preferences, this species can be classified as a moderately troglomorphic troglobiont. Besides type locality, the species was found in some other caves of Tsebelda Karst Massif: Tshalintshur Cave and Verkhnyaya Shakuranskaya Cave ( Fig. 1 ). Most probably P. kovali sp. nov. is the West Caucasian endemic. Conservation status. The new species shows restricted distribution possibly limited by caves of Tsebelda Karst Massif. According to IUCN (2012) classification the species most likely corresponds to the category Vulnerable and criterion D2 . Therefore, P. kovali sp. nov. is recommended to be included into IUCN Red List of Threatened Species along with protection of its habitats—Tsebeldinskaya Cave and complex of Shakuran caves which are type and the only localities for several invertebrate troglobiont taxa. Etymology. The new species is dedicated to my colleague entomologist and biospeleologist Dr. Alexander Koval (St. Petersburg, All-Russia Institute of Plant Protection) who has made many efforts on the exploration of the West Caucasian cave fauna including fauna of Tsebeldinskaya Cave. Remarks. Short empodia, not exceeding tip of corresponding claws, is a character that does not often occur in the species of principalis group, so the range of comparable congeners is limited by five of them (Table 3): European P. thermophilus ( Loksa, 1964 ) , Japanese P. japonicus ( Yosii, 1956 ) , Nearctic P. ashcraftensis Zeppelini, Taylor & Slay, 2009 , P. carolynae ( Christiansen & Bellinger, 1996 ) and P. marshalli ( Christiansen & Bellinger, 1996 ) . Only two of these species have claws of all legs without tunica ( P. ashcraftensis and P. marshalli ). P. kovali sp. nov. differs from P. ashcraftensis by: higher antenna/head ratio (2.3 vs. 1.8), number of Ant IV subsegments (5 vs. 6), presence of spiny setae on head (vs. usual setae), setae number on dorsal valve of Abd VI (13 vs. 12 per side), absence of corner tooth on claw III (vs. presence). From P. marshalli the new species differs by: smaller body size ( 0.9 mm vs. 1.7 mm ), absence of corner tooth on claw III (vs. presence), 7 + 7 setae on manubrium (vs. 6 + 6), presence of 1 + 1 eyes (vs. 2 + 2). P. kovali sp. nov. is similar to P. dbari sp. nov. , described above, in many respects but differs from it by antenna / head ratio (2.3 vs. 3), subsegments of Ant IV (5 vs. 7), length of sense rods of antennal III organ (4.5 vs. 10 µm), spiny setae on head dorsum (4 + 4 vs. 5 + 1 + 5), number of setae on femora II (15 vs. 13) and III (14 vs. 12), posterior dorsal seta dI-1 / claw III ratio (1.5 vs. 2.2), shape of dens setae IIIpi and IVpi (spiny vs. simple). Comparison of two species described here with others is also presented in Table 3. FIGURES 34–48. Pygmarrhopalites kovali sp. nov. : 34, chaetotaxy of head; 35, chaetotaxy of antenna; 36–48, shape of setae: 36, spine-like seta of head vertex; 37, m1 of mesothorax; 38, m1 of metathorax; 39, Ie of dens; 40, IIpe of dens; 41, IIIpi of dens, lateral and 42, dorsal view; 43, trichobothrium B, proximal part; 44, dI-1 of great abdomen; 45, ms1 of Abd VI; 46, mps3 of abd VI; 47, mpi2 of Abd VI; 48, appendices anales. FIGURES 49–51. Pygmarrhopalites kovali sp. nov. , chaetotaxy of legs: 49, foreleg; 50, mid leg; 51, hind leg. FIGURES 52–56. Pygmarrhopalites kovali sp. nov. : 52, chaetotaxy of great abdomen, red arrow directed downward points out a position of seta p below the level of trichobothrium B; 53, chaetotaxy of furca; 54, tenaculum; 55, chaetotaxy of male Abd VI; 56, chaetotaxy of female Abd VI. FIGURES 57–61. Pygmarrhopalites kovali sp. nov. : 57, habitus of mounted holotype; 58, head dorsum; 59, chaetotaxy of trichobothrial complex; 60, fragment of female Abd VI with circumanal setae, lateral view; 61, female appendices anales. TABLE ³ . Differences between Pygmarrhopalites dbari sp. nov. , P. kovali sp. nov. anđ congeners of principalis group with empođia not exceeđing claws tips