Troglopedetes spectabilis, Surakhamhaeng 1 & Deharveng 2 & Jantarit 3, 2021

Surakhamhaeng 1, Katthaleeya, Deharveng 2, Louis & Jantarit 3, Sopark, 2021, Three new species of cave Troglopedetes (Collembola, Paronellidae, Troglopedetinae) from Thailand, with a key to the Thai species, Subterranean Biology 40, pp. 129-174 : 129

publication ID	https://dx.doi.org/10.3897/subtbiol.40.73143
publication LSID	lsid:zoobank.org:pub:6B418FD9-B1F2-4D5E-AFB5-0D4DF2395D21
persistent identifier	https://treatment.plazi.org/id/63D73A9D-2C17-428B-B7FF-E79D03F02A1F
taxon LSID	lsid:zoobank.org:act:63D73A9D-2C17-428B-B7FF-E79D03F02A1F
treatment provided by	Subterranean Biology by Pensoft
scientific name	Troglopedetes spectabilis
status	sp. nov.

Treatment

1. Troglopedetes spectabilis sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 16A View Figure 16

Type locality.

Thailand, Kanchanaburi province, Sai Yok district, Tham (cave) Morakhot (14°11'02.7"N, 99°01'32.8"E, 426 m a.s.l.).

Type material.

Holotype: female on slide, Kanchanaburi province: Sai Yok district, Tham (cave) Morakhot, 14°11'02.7"N, 99°01'32.8"E, 426 m a.s.l., 28 February 2019, S. Jantarit, A. Nilsai and K. Jantapaso leg., dark zone of cave, by aspirator (sample # THA_SJ_KRI12). Paratypes: 5 paratypes on slides (all subadults), same locality and date as the holotype.

Holotype and 5 paratypes deposited in NHM-PSU, measurements of holotype in Table 1 View Table 1 .

Description.

Habitus. Highly troglomorphic, slender, with elongate legs, furca and antennae (Figs 2A View Figure 2 , 16A View Figure 16 ). Length: 1.7-2.1 mm (n = 6) (body 1.5-1.7 mm, head 0.4-0.5 mm). Fourth abdominal segment 4-6 times (n = 6, female and 5 subadults) longer than the third one along the dorsal axis. Furca well developed, about 1.1-1.2 (n = 3) times shorter than body length. Body colour white, with spots of orange pigment. Eyes absent, no ocular patch.

Chaetal types . Four types of chaetae on somites, appendages (except antennae) and mouthparts: scales, present on antennal segment I and II, head, body and ventral side of the furca, absent on legs and ventral tube; ordinary chaetae on all body parts; S-chaetae and trichobothria on tergites; hairs devoid of sockets on outer maxillary lobe. Chaetal types on antennae are much more diverse and described separately further.

Pseudopores (Figs 2E View Figure 2 , 3A-D View Figure 3 , 4G View Figure 4 , 5B View Figure 5 , 6B View Figure 6 , 6D View Figure 6 ). Pseudopores present as round flat disks larger than mac sockets, on antennae, head and tergites. Head pseudopore sometimes present asymmetrically on one side only (Fig. 2E View Figure 2 ). Dorsal pseudopore formula: 1/1, 1/1, 1, 1, 1+4 (Figs 2E View Figure 2 , 3A-D View Figure 3 ). On antenna, 2 psp detected ventro-distally on Ant. I, 3 ventro-distally on Ant. II and 1 ventro-distally on Ant. III (Figs 5B View Figure 5 , 6B View Figure 6 , 6D View Figure 6 ). On head, 1 psp close to antennal basis (Fig. 2E View Figure 2 ). On legs, psp present externally on coxae (2 for legs I and II and 2-(3) for leg III). On manubrium, 2 psp on the dorso-distal plaque (Fig. 4G View Figure 4 ); on each dens, 4 psp dorso-basally near the internal spine row (Fig. 4G View Figure 4 ).

Mouthparts. Clypeus with 11 mac, symmetrically arranged: 9 ciliated posteriorly and 2 smooth anteriorly (Fig. 2F View Figure 2 ). Labral formula 4/5,5,4 (Fig. 2I View Figure 2 ; prelabral chaetae short, bent and ciliated, labral chaetae thinner, longer, smooth and acuminate, those of the distal row slightly larger and longer than those of the median row; its anterior line not concave in V or U-shape, contrary to T. kae ( Jantarit et al. 2020). Ventro-distal complex of labrum well differentiated, asymmetrical, with 2 distal combs (a larger one with 8-12 teeth on the left side, a smaller one with 15-19 minute teeth on the right side) and an axial pair of sinuous tubules (Fig. 2C View Figure 2 ). Distal part of labrum not adorned with spines dorso-distally. Labial palp similar to that described by Fjellberg (1999) for Troglopedetes sp., with strong papillate chaetae. Number of guards for each major papillate chaetae: A (0), B (5), C (0), D (4) and E (4); lateral process subcylindrical, reaching above the apex of papilla E (Fig. 2B View Figure 2 ); 5 proximal chaetae. Chaetae of labial basis as M1m2rel1l2, with M1 ciliated, m2, e and l1 subequal and smooth, r shorter than others and smooth, l2 short, smooth and acuminate (Fig. 2H View Figure 2 ). Outer maxillary lobe with 1 papillate chaeta, 1 basal chaeta and 2 sublobal hairs, shorter than the others (Fig. 2G View Figure 2 ). Maxillary head with a 3-toothed claw, several stout shortly ciliated lamellae not observed in detail and 2 thin elongate structures (1 dorsally and 1 ventrally), like in T. kae ( Jantarit et al. 2020). Mandible head strong, asymmetrical (left side with 4 teeth, right side with 5); molar plate with 3 strong pointed basal teeth, and other 2-3 inner distal teeth, identical in both mandibles.

Antennae (Figs 2A View Figure 2 , 2D View Figure 2 , 5 View Figure 5 - 7 View Figure 7 ). Antennae extremely elongated (2,175-2,780 µm, n = 6), 1.45-1.64 times longer than body+head length (n = 3), 5.5 times (n = 4) longer than the cephalic diagonal. Ant. IV subdivided into two segments, asymmetrically arranged with Ant. IVa longer than IVb (Fig. 7E View Figure 7 ) (0.6 : 0.4, n = 4), without apical bulb (Fig. 7C View Figure 7 ). Lengths of antennal segments I to IV (IVa+IVb) as 1:1.7:2:2.7 (average, n = 4). Antennal chaetae (scales, 5 types of ordinary chaetae, 14 types of S-chaetae and subapical organit) described separately.

General chaetotaxy (Figs 2E View Figure 2 , 3A-D View Figure 3 ). Body densely covered with oval scales; ventro-lateral scales larger than dorsal ones; posterior scales of tergites larger than anterior ones (17-59 µm long).

Dorsal macrochaetae formula: 4,2/9,4/0,2,4,3 (Figs 2E View Figure 2 , 3A View Figure 3 ). Trichobothrial pattern : 1/0, 0/0, 2, 3, 3 (Figs 2E View Figure 2 , 3A View Figure 3 ). Trichobothrial complexes well developed with modified mes of various sizes (Fig. 3A-D View Figure 3 ), described below for each segment. The figured mes pattern is not complete.

Head chaetotaxy. Head with 10-11 peri-antennal mac in line on each side, with 4+4 central mac (chaetae A, B, D, G of Deharveng and Gers (1993); AMS = A3, M2, M1 and S3), absence of the chaetae C, E and F. Cephalic mes short, feebly serrated, equal, 9+9 symmetrically arranged (Fig. 2E View Figure 2 ). One lateral cephalic trichobothria much shorter than the closest mac on each side; suture zone not visible (Fig. 2E View Figure 2 ). Head dorsally densely covered with round to oval scales (25-35 µm long).

Ventral chaetotaxy of head densely covered with oval scales (65-72 µm long), postlabial chaetae along the linea ventralis as 3 smooth mes anteriorly and 2 smooth chaetae laterally, one mac and an oblique line of 7-8 mes posteriorly on each side (Fig. 2H View Figure 2 ).

Tergite chaetotaxy . Th. II with a collar consisting of a few rows of mac along its anterior and antero-lateral margins, a compact group of 6 central mac on each side ("P3 complex" of Soto-Adames et al. (2014) and 3 antero-lateral mac; 1 antero-lateral ms; 1 antero-lateral sens; 3 short mic postero-laterally, and a few others not counted centrally (Fig. 3A View Figure 3 ).

Th. III with 4 mac by side (a group of 3 central and 1 anterior to them), 1 sens at antero-lateral margins, and about 16 mac or long mes at lateral margins (Fig. 3A View Figure 3 ).

Abd. I without central mac, with 1 ms laterally on each side, a row of 3 mics below psp, a6 (sensu Soto-Adames 2015) absent, and 5 mes laterally (Fig. 3A View Figure 3 ).

Abd. II with 2 tric on each side and 6 modified mes around them (2 around the internal tric and 3-4 near external tric), 2 mac (1 near internal tric and 1 near external tric), 1 sens near internal tric, 2 mic close to external tric), at least 6 other mes sockets visible at lateral margins (not drawn) (Fig. 3A, B View Figure 3 ).

Abd. III with 3 tric on each side (1 internal, 2 external) and 9-10 modified mes around tric (3 near internal tric, 6-7 near the two external tric); 4 mac (1 near internal tric and 3 near external tric); 1 sens anterior to internal tric and ms not seen; at least 7 mes at lateral margins (Fig. 3A, C View Figure 3 ).

Abd. IV with 3 tric on each side (2 antero-lateral, 1 postero-lateral) and about 7-11 modified mes around the two antero-lateral tric; postero-lateral tric without modified mes. Mac distributed as 3 central on each side (1 antero-external to pseudopore, 2 anterior to posterior tergite margin), 1 near postero-lateral tric, and at least 4 external, mixed with at least 13 mes or smaller mac on lateral to posterior margins; 2 sens; at least 9 S-like chaetae sensu Lukić et al. (2015) anteriorly, and at least 5 mes or short S-like chaetae uniformly distributed; at least 3 serrated mes in line in the posterior row along pseudopore line, from medium to short size (Fig. 3A, D View Figure 3 ).

Abd. V with 2 sens detected on each side, and several ordinary chaetae from mes to mac, not counted (Fig. 3A View Figure 3 ). Abd. VI chaetotaxy not analyzed.

Legs (Fig. 4A-C View Figure 4 ). Legs long. Tita III 1.3-1.4 times longer than the head diagonal, slightly longer than Tita I and II. Legs devoid of scales, mostly covered with ordinary ciliated chaetae of various length, from mes to mac. Trochanteral organ of leg III with 19-21 smooth, straight, unequal spiny chaetae (n = 4) (Fig. 4E View Figure 4 ). Tibiotarsus chaetotaxy mostly composed of strong ciliated-serrated mes, the basal ones longer and thicker (52-69 µm), slightly shorter distally (up to 35-40 µm). Distal row with 9-10 subequal ciliated mes and a dorso-apical tenent hair clavate on tita; a ventro-distal strong smooth erected chaeta present on Tita III (Fig. 4B View Figure 4 ). Praetarsal mic minute (3.5-4 µm), clearly seen in one side (Fig. 4B View Figure 4 ). Unguis slender and long (56-66 µm long, 12-15 µm wide at basis), 10 times shorter than tita. Claw I and II with 2 strong unpaired inner teeth at 50-57% and 80-89%, and a pair of inner basal teeth of equal size (Fig. 4A View Figure 4 ); Claw III with a very tiny tooth at 88% of inner edge (Fig. 4B, C View Figure 4 ), outer edge with a minute tooth at 19-25% usually inconspicous; unguiculus pointed, narrow, lanceolate and elongate, 0.5-0.7 times shorter than the claw, its external edge with at least 9 toothlets (Fig. 4B View Figure 4 ).

Ventral tube (Fig. 4D View Figure 4 ). Ventral tube about 4 times longer than wide, with 3+3 long serrated mac anteriorly and 6 mes (2 ciliated and 4 smooth) on each lateral flap; posterior side not visible.

Furca complex (Fig. 4G, H View Figure 4 ). Tenaculum with 4 teeth on each ramus, of decreasing size from the basal to the distal one, on a prominent, irregular body, with a postero-basal strong, densely serrated, distally bent chaeta. Manubrium about 1.28 times (n = 5) shorter than the mucrodens (mucro+dens). Manubrium dorsally with subequal ciliated mes (none smooth), irregularly arranged in 3-4 rows in two longitudinal stripes separated by a glabrous axial stripe, external row of chaetae distally with at least 11 long ciliated mes, dorso-distal plaque with 4+4 mes and 2+2 pseudopores (Fig. 4G View Figure 4 ). Ventrally with a dense cover of round to oval (30-60 µm) and thin elongated scales (35-70 µm). Dens straight, elongate, hairy, slightly and progressively tapering, dorsally with 2 rows of spines, mixed with ciliated mes of various length, thickness and shape. Dorso-external row with 21-24 spines, dorso-internal row with 40-46 spines (asymmetries between dentes); external spines larger and less sclerotized than the internal ones. Some short ciliated mes interspersed with spines in the external row; dorsally between the two rows of spines a mix of short and long ciliated mes, irregularly arranged in one row distally turning to 3-4 rows proximally; laterally, many short ciliated mes; dorso-distally, 3-(4) stronger ciliated mes; 4+4 psp on dorso-basally between the two rows of spine (Fig. 4G View Figure 4 ). Dens ventrally entirely and densely scaled, the scales elongate (25-60 µm) (oval shape distally), arranged in short lines from 3-5 (distally) to 6-8 scales (proximally) (Fig. 4G View Figure 4 ). Mucro rather stout, short, 13.5-14.4 (average 14, n = 5) times shorter than dens (Fig. 4G, H View Figure 4 ), with 4 main teeth, the apical one blunt and strong, the subapical one acute and strong, a latero-distal one small and acute, and 1 dorso-basal, minute, acute and strong, acute with one toothlet basally (Fig. 4H View Figure 4 ).

Genital plate (Fig. 4F View Figure 4 ). Female genital plate with 2+2 mic.

Ecology.

Troglopedetes spectabilis sp. nov. exclusively inhabits a chamber in the dark zone of a cave. Specimens were found in an oligotrophic habitat with a very humid and wet environment on muddy ground. The air temperature in the chamber was 23.5-24.3 °C, soil temperature was 22.9-23.1 °C and the relative humidity was 84%. The cave is undisturbed and rather difficult to access (due to the steep slope up to the entrance). It is located in dry evergreen forest mixed with bamboo forest at moderate altitude (426 m. asl.). Some simple infastructure has been introduced into the cave, including a metal ladder at the entrance.

Etymology.

The species name is derived from the Latin word spectabilis, meaning “remarkable” or “admirable” and referring to its extremely long antennae.

Remarks.

Troglopedetes spectabilis sp. nov. is the most highly troglomorphic species of Troglopedetes . It is clearly distinct from other species of the genus by the extreme length of its appendages, especially the antennae (the ratio of antenna: head is 5.5), by its claw complex and by its furca (Table 1 View Table 1 ). Chaetae m2 and l1 of labial basis are smooth whereas they are ciliated in all other described species in the country. Central area of head has A, B, D, G macrochaetae. Dens of T. spectabilis sp. nov. is very long with 40-46 internal spines and 4 psp, while the other species of the genus in Thailand have only 2 psp. A most unexpected character of this species is the very different claw morphology of leg I-II and leg III checked in several specimens, which may have taxonomic and evolutionary implication that will be discussed in future works.