Coecobrya cavicola, Nilsai & Zeppelini & Bellini & Lima & Jantarit, 2022

Nilsai, Areeruk, Zeppelini, Douglas, Bellini, Bruno C., Lima, Estevam C. A. & Jantarit, Sopark, 2022, First record of the boneti-group of Coecobrya Yosii, 1956 (Collembola Entomobryidae) from Thailand, with the description of three new cave species of the genus, Zootaxa 5214 (3), pp. 365-392 : 374-381

publication ID	https://doi.org/ 10.11646/zootaxa.5214.3.3
publication LSID	lsid:zoobank.org:pub:300E9C35-BA31-4FC1-AA32-8740609A3A11
DOI	https://doi.org/10.5281/zenodo.7389117
persistent identifier	https://treatment.plazi.org/id/03B787B6-8B55-BF73-B9FA-FF49FF79FC2B
treatment provided by	Plazi
scientific name	Coecobrya cavicola
status	sp. nov.

Treatment

Coecobrya cavicola View in CoL sp. nov. Nilsai, Zeppelini & Jantarit

Figs 1B View FIGURE 1 , 6‒9 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 , Table 1

Type material. Holotype: female on slide. Thailand, Phrae province, Long district , unnamed cave, altitude 181 m a.s.l., approximately 18.02°N 099.94°E. 16 May 2018 S. Jantarit, A. Nilsai, K. Sarakhamhaeng and K. Jantapaso leg. (sample # THA_SJ_ PRE01 ), dark zone of the cave, by entomological aspirator. GoogleMaps

Paratypes: same data as holotype, four specimens (two females and two subadults on slides)

Additional material: same data as holotype, six specimens (in ethanol) deposited in NHM-PSU and six specimens (in ethanol) deposited in CRFS-UEPB.

Holotype and four paratypes on slides deposited in NHM-PSU.

Description. Habitus ( Figs 1B View FIGURE 1 , 6A View FIGURE 6 ). Medium sized Entomobryidae . Body length 1.3‒1.5 mm (holotype 1.3 mm). Eyes absent. Color: whitish in alcohol. Body slender, not bent nor humped at the level of Th. II., moderately long antennae, legs and furca. Th. II slightly larger than the Th. III; Abd. IV about 3.05‒3.93 times as long as the Abd. III along the dorsal midline.

Pseudopores ( Figs 7A View FIGURE 7 , 8A, D View FIGURE 8 , 9A‒E View FIGURE 9 ). Pseudopores present as round flat disks, smaller than mac sockets ( Fig. 7A View FIGURE 7 ), except for the coxae and manubrium where psp are as large as mac sockets. Pseudopores present on various parts of the body: antennae, head, tergites, coxae and manubrium. On antennae, psp located ventro-apically between the tip of antennal segments and the chaetae of the apical row, or just below the apical row of chaetae (two on Ant. I, 2‒3 on Ant. II, and three on Ant. III). On head, 1‒2 psp located externally on each peri-antennal area ( Fig. 8A View FIGURE 8 ). On tergites, 1+1 psp close to the axis from Th. II to Abd. IV ( Figs 8D View FIGURE 8 , 9A‒E View FIGURE 9 ). Coxae I, II and III with 1‒ 2, 2‒ 3, and 1‒2 psp respectively, located close to longitudinal rows of chaetae. On manubrium, 2+2 dorso-apical ones on the manubrial plaques ( Fig. 7A View FIGURE 7 ).

Clypeus and mouthparts ( Figs 6D‒E, G View FIGURE 6 , 8B View FIGURE 8 ). Clypeal area with nine chaetae arranged in three rows, with three rather long smooth chaetae in the prefrontal area; 1+1 rather short ciliated and 1+1 rather long smooth chaetae of subequal sizes in the facial area; and 1+1 rather long smooth lateral chaetae anteriorly ( Fig. 6G View FIGURE 6 ). Prelabral and labral chaetae 4/5, 5, 4, all thin and smooth; median three chaetae of the second line longer than the lateral ones (21‒23 vs. 9 ‒11 µm); median three chaetae of the third line longer than the lateral ones (23‒25 vs. 26‒28 µm) ( Fig. 8B View FIGURE 8 ). Distal border of the apical non-granulated median area of the labrum with a relatively narrow median U- or Vform intrusion (U form in the Fig. 8B View FIGURE 8 ) into the granulated area dorsally; apical edge without spines, lacking clear papillae. Maxillary outer lobe with one basal and one apical chaetae (basal chaeta thicker than the apical one) and three smooth sublobal hairs (36‒38 vs. 17‒19 µm) ( Fig. 6E View FIGURE 6 ). Labial palp with 0, 5, 0, 4, 4 guards for papillae A‒E. Lateral process of labial palp subcylindrical, as thick as normal chaetae with tip beyond the apex of the labial papilla ( Fig. 6D View FIGURE 6 ). Mandible apex strong, asymmetrical (left with four, right with five teeth).

Antennae ( Figs 6A, C View FIGURE 6 ). Antennae moderately long, approximately 2.4–2.6 times as long as the cephalic diagonal. Antennal segments ratio as I: II: III: IV = 1: 1.13–1.55: 1.16–1.33: 1.90–2.06 (N = 3). Antennal segments not subdivided nor annulated. Antennal chaetal types not analysed in detail. Smooth spiny mic at base of antennae: three dorsal, three ventral on Ant. I, one internal, one external and one ventral on Ant. II, one smooth ventral on Ant. I, smooth straight long chaetae on antennae present. Ant. I ventrally with many smooth spiny mic of various sizes in its basal part, many subcylindrical, hyaline sens in its middle to apical part, and many long smooth straight chaetae. Dorsal Ant. II with two paddle-like chaetae. Ant. III organ with five sens; sens one and four subequal, hyaline; sens five acuminate, dark and shorter; sens two and three swollen. Ant. IV not subdivided, without the apical bulb. Subapical organite not much swollen, slightly enlarged apically, inserted dorsally ( Fig. 6C View FIGURE 6 ).

Dorsal head chaetotaxy ( Fig. 8A View FIGURE 8 ). Dorsal cephalic chaetotaxy with five antennal chaetae (An1–2, An3a2, An3a; An3 as mic), four anterior (A0, A2–3 and A5), three median (M1–2, M4) and eight sutural mac (S0, S1– 4, 4e, 5–6), Gr. II with five mac (Pi1–3, Pa1, Pp1a); 5+5 scale-like structures present below the sutural mac, inside the integument (like in Fig. 4D View FIGURE 4 ), (socket of scale-like structures not detected under SEM) (like in Fig. 4C View FIGURE 4 ); a pair of short cephalic trichobothria, external and close to the middle of the head ( Fig. 8A View FIGURE 8 ).

Ventral head chaetotaxy ( Figs 6B, F, H View FIGURE 6 ). Chaetae of labial basis all smooth M 1m 2rel 1 l 2 (or Mimrel1l2 sensu Zhang & Pan 2020), chaetae m, e and l 1 subequal, r thin and shortest, ratio of r to m2 0.10‒0.19 ( Figs 6B, 6F View FIGURE 6 ). Postlabial chaetae H1 ciliated, X, X 2, X 4 as spiny mic; X 3 absent ( Fig. 6F View FIGURE 6 ). Each side of the cephalic groove with seven chaetae, the first anterior 1 st –3 rd always long and smooth, 4 th –7 th always ciliated, sometimes small or long chaetae ( Figs. 6F. 6H View FIGURE 6 ).

Tergites ( Figs 8D View FIGURE 8 , 9A–F View FIGURE 9 ). Th. II with four (m1, m1i, m2, m2i) medio-medial, four (a5, m4, m4i, m4p) mediosublateral and 34 posterior mac; 1+1 ms and 2+2 sens laterally ( Fig. 8D View FIGURE 8 ). Th. III with 40 mac, m6 and m6ai as mac, 2+2 sens laterally ( Fig. 9A View FIGURE 9 ). Abd. I with eight (a1, a1e, a2‒3, a5, m2–4) central mac, 1+1 ms and 1+1 sens laterally ( Fig. 9B View FIGURE 9 ). Abd. II with five (a2‒3, m3, m3e, m3ep) central and one (m5) lateral mac. 2+2 tric without modified surrounding chaetae, 1+1 sens laterally and 1+1 sens above m3 ( Fig. 9C View FIGURE 9 ). Abd. III with two (a2, m3) central, and three (am6, pm6, p6) lateral mac. 3+3 tric without modified surrounding chaetae, 1+1 sens laterally, 1+1 sens near a2 ( Fig. 9D View FIGURE 9 ). Abd. IV with seven central mac (A3, A5‒6, B4‒6, Sm) and nine (D3, E2, E2p, E3–4, Ee8, F1–2, F3a) lateral mac, 2+2 tric and about 8 long S-like chaetae anteriorly, without modified chaetae ( Fig. 9E View FIGURE 9 ). Abd. V with at least eight obvious mac (a5, m2‒3, m5, p1, p3‒5) and several mes or small mac, and 3+3 sens ( Fig. 9F View FIGURE 9 ). Abd. VI not analysed.

S-chaetae formula from Th. II to Abd. V: 2+ms, 2/1+ms, 2, 2, ≈ 8, 3; ps and as sens on Abd. IV 1/2 as long as S-like chaetae ( Figs 8D View FIGURE 8 , 9A–F View FIGURE 9 ).

Legs ( Figs 7C‒F View FIGURE 7 , 8C View FIGURE 8 ). Legs moderately long; tita of leg III slightly longer than tita of legs I and II. Legs devoid of scales, covered with ordinary ciliated chaetae of various lengths, mic not seen. Tibiotarsi II and III ( Fig. 7C View FIGURE 7 ) with one large inner ciliated mac at about 1/3 from basal side. Trochanteral organ with about 18 smooth, straight, unequal spinelike chaetae ( Fig. 8C View FIGURE 8 ). The distal whorl of tita with 9‒10 subequal ciliated mes, irregularly arranged, and dorso-apical pointed tenent hair present. Smooth, thin and long chaeta close to the tenent hair absent. Ventro-distal smooth chaeta of tita III thick, erected, pointed, rather short. Claw elongated. Unguis with one small unpaired inner tooth at 53‒61%, and a pair of subequal basal teeth at about 46‒50% of inner edge from basis. Unguiculus approximately 2/3 as long as the inner edge of the claw, narrow and not swollen baso-externally, pointed apically, with a few minute outer teeth, often inconspicuous in the middle of its length in claw II and III, without outer teeth in claw I ( Figs 7D‒F View FIGURE 7 ).

Ventral tube ( Figs 8E‒G View FIGURE 8 ). Ventral tube two to three times longer than wide. Lateral flaps with 6‒8 + 6‒8 chaetae, all smooth chaetae of unequal sizes. ( Fig. 8E View FIGURE 8 ). Anterior face with 6‒8+6‒8 ciliated chaetae, 2 of them apically larger than the others ( Fig. 8G View FIGURE 8 ); posterior face with 2+2 more apical smooth chaetae 1 unpaired ciliated chaeta just under the pair of smooth chaetae, 1+1 smooth chaeta at the distal region, the middle chaetae with seven chaetae (three smooth and four ciliated chaetae of unequal sizes) ( Fig.8F View FIGURE 8 ).

Furcal complex ( Figs 6I View FIGURE 6 , 7A‒B View FIGURE 7 ). Tenaculum with four large teeth of decreasing sizes from the basal to the distal one on each ramus, on a prominent, irregular corpus, with a postero-basal strong serrated chaeta bent distally. Mucrodens 1.30‒1.33 times longer than the manubrium. Furcula without smooth chaetae. Manubrium densely covered by ciliated chaetae both dorsally and ventrally. Manubrial plaque with 2+2 pseudopores and two ciliated chaetae ( Fig. 7A View FIGURE 7 ). Distal part of the ventral manubrium with 10+10 ciliate chaetae ( Fig. 7B View FIGURE 7 ). Dens without spines, annulated and covered with ciliated chaetae on both sides. Distal smooth part of dens as long as the mucro. Mucro strong and falcate, basal spine long, beyond the tip of the mucronal tooth ( Fig. 6I View FIGURE 6 ).

Genital plate. Female genital plate with 2+2 genital mic.

Ecology. Coecobrya cavicola sp. nov. is restricted to the dark zone of the cave where it was found, in an oligotrophic environment with a rather large population of individuals. Most specimens were found on the cave floor, which was muddy ground, on stalagmites and on the rock walls. The temperature in the dark zone was 25.0‒ 26.2°C and the relative humidity was 85‒91%.

Etymology. The name of the new species is derived from the Latin stem “ cav- ” which means “hole” and “ col- ” which means “to dwell”, referring to the habitat of this new species which is restricted to the subterranean environment.

Remarks. The overall profile of Coecobrya cavicola sp. nov. is intermediate between the non-troglomorphic and troglomorphic groups of species, as it is rather small, and its antennae are not elongated compared to other described highly troglomorphic species (see Table 3). However, here it is placed into the troglomorphic group as it has rather moderately long appendages, slender and elongated claws, as well as being eyeless and depigmented. It is also worth noting that its habitat is an oligotrophic area within the wet and humid dark zone of a cave. Among all the described troglomorphic Coecobrya species in Thailand, C. cavicola sp. nov. differs from them especially in the number of posterior mac on Th. II (20), and the number of mac on Abd. I (5), ( Table 1). It is apparently closer to C. cavicta from a cave in Satun province, southern Thailand, by having similar antennal length (Ant./head = 2.4‒2.6 times); long smooth straight chaetae on Ant. II present; number of dorsal head in A (4 mac) and M areas (3 mac); number of sublobal hairs of labial palp (3), number of mac on the medio-sublateral area of Th. II (3); lateral mac of Abd. III (3) and pointed tenent hairs. However, the new species is clearly different from C. cavicta in: the number of dorsal head mac of An area (2 vs 4); number of chaetae in Gr.II (5 vs 4); labial chaetae formula (M 1m 2rel1l2 vs mrel1l2); number of chaetae along the cephalic groove (3s1‒4c vs 3‒4s7‒8c); number of mac on medio-medial area of Th. II (4 vs 3); posterior mac of Th. II (34 vs 30‒31); mac on Th. III (40 vs 35); central mac on Abd. II (5 vs 3); central mac on Abd. III (2 vs 1); ms on And. III (present vs absent); lateral mac on Abd. IV (8 vs 11); number of smooth chaetae of the trochanteral organ (18 vs 15‒16); number of chaetae on manubrial plaque (2 vs 4); number of chaetae on ventraldistal part of manubrium (10 vs 13) and mucronal spine (beyond vs nearly reaching the mucronal apex).