Troglopedetes meridionalis, Jantarit & Surakhamhaeng & Deharveng, 2020

Jantarit, Sopark, Surakhamhaeng, Katthaleeya & Deharveng, Louis, 2020, The multiformity of antennal chaetae in Troglopedetes Joseph, 1872 (Collembola, Paronellidae, Troglopedetinae), with descriptions of two new species from Thailand, ZooKeys 987, pp. 1-40 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.987.54234
publication LSID	lsid:zoobank.org:pub:C46FAFC0-2322-47A6-8F5B-7DBC770C26EF
persistent identifier	https://treatment.plazi.org/id/9FA46FCC-4ED7-4DE0-9362-EC8425E63AAD
taxon LSID	lsid:zoobank.org:act:9FA46FCC-4ED7-4DE0-9362-EC8425E63AAD
treatment provided by	ZooKeys by Pensoft
scientific name	Troglopedetes meridionalis
status	sp. nov.

Treatment

Troglopedetes meridionalis sp. nov. Figures 11 View Figure 11 , 12 View Figure 12 , 13 View Figure 13 , 14 View Figure 14 , 15 View Figure 15 , 16 View Figure 16

Type material.

Holotype male and four paratypes (one female, three subadults) on slides. Thailand: Chumphon Province: Lang Suan district, Tham Don Non (Tapan), 9°54'14"N, 99°02'41"E, ca 60 m a.s.l., 25 Jul. 2015, S. Jantarit leg., dark zone of cave, by aspirator (sample # THA_SJ_CPN01). Holotype and two paratypes deposited in NHM-PSU. Two paratypes deposited in MNHN. Measurements of holotype in Table 2 View Table 2 .

Description.

Habitus. Slightly troglomorphic, slender, with elongate legs, furca and antennae (Figs 1 View Figure 1 , 11A View Figure 11 ). Body length 1.3-1.5 mm. Fourth abdominal segment 3 × as long as the third one along dorsal axis. Furca well developed, ca. 2 × 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 antennae I and II, head, body and 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 12C View Figure 12 , 13D View Figure 13 , 15A, B, D View Figure 15 ). Pseudopores present as round flat disks larger than mac sockets, on antennae, head and tergites. Dorsal pseudopore formula: 1-(2)/1, 1/1, 1, 1, 1+4 (Figs 11J View Figure 11 , 15A View Figure 15 ). On antenna, 1-(2) psp detected ventro-distally on Ant. I., one ventro-distally on Ant. II and one ventro-distally on Ant. III, sometimes not clearly seen (Figs 12C View Figure 12 , 13D View Figure 13 ). On head, 1-(2) psp close to antennal basis. On legs, psp present externally on coxae (two for legs I and II and 2-(3) for leg III). On manubrium, two psp on each dorso-distal plaque, on dens (new location for Troglopedetes ) two psp dorso-basally near the internal spine on each side (Fig. 16E View Figure 16 ).

Mouthparts. Labral formula 4/5,5,4; prelabral chaetae short, bent and ciliated, labral chaetae thinner, smooth and acuminate, those of the distal row slightly shorter than those of the median row. Ventro-distal complex of labrum well differentiated, asymmetrical, with two distal combs (a larger one with 6-8 teeth on the left side, a smaller one with more than ten minute teeth on the right side) and an axial pair of sinuous tubules. Distal part of labrum not adorned with spines dorso-distally. Labial palp similar to that of T. kae sp. nov. (Fig. 11B View Figure 11 ). Chaetae of labial basis as M1M2REL1l2. Chaetae M1, M2, E and L1 subequal and ciliated, R shorter than others and ciliated, l2 short, smooth and acuminate (Fig. 11D, G View Figure 11 ). Outer maxillary lobe with one papillate chaeta, one basal chaeta and two sublobal hairs, shorter than others (Fig. 11C View Figure 11 ). Maxillary head with a 3-toothed claw, several stout shortly ciliated lamellae not detailed here; special structures present on the maxilla head, i.e., a thin elongate structure, arising from the basis of the maxilla head and reaching claw basis; close to it a spiny structure and a thin structure in an opposite side (Fig. 11F View Figure 11 ). Mandible heads strong, asymmetrical (left side with four teeth, right side with five teeth); molar plate with three strong pointed basal teeth, and other two or three inner distal teeth, identical in both mandibles (Fig. 11E View Figure 11 ).

Ventral chaetotaxy of head (Fig. 11D, G View Figure 11 ). Head densely covered with oval scales (40-50 µm), postlabial chaetae along the linea ventralis as three mes anteriorly, one mac and one oblique line of four or five mes posteriorly on each side.

Antennae (Figs 11H-I View Figure 11 , 12A-D View Figure 12 , 13A-F View Figure 13 , 14A-C View Figure 14 ). Antennae shorter than body, ca. 2 × (n = 3) as long as cephalic diagonal. Ant. IV subdivided into two subequal segments, without apical bulb. Lengths of antennal segments I to (IVa+IVb) as 1:1.8:1.5:2.9 (average, n = 3). Antennal chaetae (scales, five types of ordinary chaetae, 13 types of S-chaetae and subapical organite) described separately. Antennal scales oval, present dorsally only on Ant. I and II and ventrally on Ant. II, absent ventrally on Ant. I, and absent on Ant. III and IV (Figs 11H View Figure 11 , 12A-D View Figure 12 , 13D-F View Figure 13 ).

Dorsal chaetotaxy (Figs 11J View Figure 11 , 15A, B, D View Figure 15 ). Dorsal macrochaetae formula: 1,4/8,4/0,2,4,3 (Figs 11J View Figure 11 , 15A View Figure 15 ). Trichobothrial pattern: 1/0, 0/0, 2, 3, 3 (Figs 11J View Figure 11 , 15A, B, D View Figure 15 ). Trichobothrial complexes well developed with modified mes of various sizes (Fig. 15A-D View Figure 15 ) as described below for each segment. The mes pattern is not complete. Head with 12 or 13 peri-antennal mac in line on each side; with 1+1 central mac (chaetae A of Deharveng and Gers 1993), chaetae B-F absent, at least 9+9 cephalic mes short, feebly serrated, equal in size, symmetrically arranged (Fig. 11J View Figure 11 ). One lateral cephalic trichobothria much shorter than closest mac on each side; suture zone visible, without associated mac (Fig. 11J View Figure 11 ). Head dorsally densely covered with round to oval scales (20-35 µm). Body densely covered with oval scales (15-50 µm).

Th. II collar consisting of a few rows of mac along its anterior and antero-lateral margins, a compact group of six central mac on each side ("P3 complex") and two antero-lateral mac; one antero-lateral ms; one antero-lateral sens; two or three short mic laterally, and a few others not counted centrally (Fig. 15A View Figure 15 ).

Th. III with four mac on each side (a group of three central and one anterior to them); one sens at antero-lateral margins; one mic laterally; and ca. 11+11 mac or long mes at lateral margins (Fig. 15A View Figure 15 ).

Abd. I without central mac, with one ms laterally on each side; two or three mic arranged in line externally to pseudopore and two larger lateral mic; three mes laterally (Fig. 15A View Figure 15 ).

Abd. II with two tric on each side and six or seven modified mes around them (two around the internal tric and four or five near external tric), two mac (one near internal tric and one near external tric), one sens near internal tric; three mic (one close to internal tric and two close to external tric), others mes sockets internally visible, not counted (Fig. 15A, B View Figure 15 ).

Abd. III with three tric on each side (one internal, two external) and nine or ten modified mes around tric (two near internal tric and seven or eight near the two external tric); four mac (one near internal tric and three near external tric); one sens anterior to internal tric and one ms posterior to the two external tric; two mic/mes external to the external mac; several mes at lateral margins, not counted (Fig. 15A, C View Figure 15 ).

Abd. IV with three tric on each side (two antero-lateral, one postero-lateral); and ca. 6-9 modified mes around the two antero-lateral tric; postero-lateral tric without modified mes. Mac distributed as three central on each side (one antero-external to pseudopore, two anterior to posterior tergite margin), one near postero-lateral tric, and four or five external, mixed with many mes or smaller mac on lateral to posterior margins (not counted); probably three sens anteriorly; at least seven S-like chaetae sensu Lukić et al. (2015), and several mes or S-like chaetae uniformly distributed (not counted); six serrated mes in line in the posterior row (one near axis and five along pseudopore line, from medium to short) (Fig. 15A, D View Figure 15 ).

Abd. V with only two sens detected on each side, and several ordinary chaetae from mes to mac in size (Fig. 15A View Figure 15 ). Abd. VI chaetotaxy not analysed.

Legs (Fig. 16A, B View Figure 16 ). Legs long; Tita III as long as 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 11-13 smooth, straight, unequal spiny chaetae (Fig. 16B View Figure 16 ). Tibiotarsus chaetotaxy mostly composed of strong ciliated-serrated mes, basal ones longer and thicker (60 µm), the distal ones slightly shorter (up to 15-20 µm). Distal row with ten subequal ciliated mes and a dorso-apical tenent hair thin, smooth and acuminate on all tita; a ventro-distal strong smooth erected chaeta present on Tita III (Fig. 16A View Figure 16 ). Praetarsal mic minute (2.5-3 µm, Fig. 16A View Figure 16 ). Unguis slender and relatively short (27-30 µm long, 6-7 µm wide at basis), 8-9 × shorter than tita; with one rather strong tooth at 50-55% of inner edge and a pair of inner basal teeth of unequal size (Fig. 16A View Figure 16 ). Unguiculus acuminate, 0.6 × as long as claw, its external edge with a minute outer basal tooth, sometimes inconspicuous (Fig. 16A View Figure 16 ).

Ventral tube (Fig. 16C View Figure 16 ). Ventral tube 4 × longer than wide; with 3+3 long serrated mac anteriorly and six mes (two ciliated and four smooth) on each lateral flap (Fig. 16C View Figure 16 ); posteriorly with many long ciliated mes, not suitable for observation in available specimens.

Furcal complex (Fig. 16D-F View Figure 16 ). Tenaculum with four large 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 (Fig. 16D View Figure 16 ). Manubrium slightly shorter than mucrodens (ca. 0.95 ×). 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 5-7 long ciliated mes, dorso-distal plaque with 4+4 mes and 2+2 pseudopores. Ventrally, dense cover of round to oval (20-38 µm) and thin elongated scales (20-25 µm).

Dens straight, elongate, hairy, slightly and progressively tapering, dorsally with two rows of spines, mixed with ciliated mes of various length, thickness and shape. Dorso-external row with 17-20 subequal spines, dorso-internal row with 30-37 subequal spines (asymmetries between dentes); external spines larger and less sclerotised than internal ones. 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; 2+2 psp on dorso-basally between the two rows of spine, sometimes inconspicuous. Dens ventrally entirely and densely scaled, scales elongate (20-38 µm), arranged in short lines from 3-5 (distally) to 6-8 scales (proximally) (Fig. 16E View Figure 16 ).

Mucro rather stout, short, 12-15 × shorter than dens (Fig. 16E, F View Figure 16 ), with four main teeth, the apical one blunt and strong, the two subapical ones smaller, the dorso-basal one slightly longer with one or two toothlets basally (Fig. 16F View Figure 16 ).

Genital plate. Genital plate not seen.

Ecology.

Troglopedetes meridionalis sp. nov. was found in small populations in the dark zone of a cave, foraging on a small patch of old and humid bat guano.

Etymology.

The name of the species, meridionalis , means southern in Latin, referring to the location of the species in the southern part of peninsular Thailand.

Remarks.

Troglopedetes meridionalis sp. nov. is the only species of the genus with one medial head macrochaeta. It is similar to T. convergens Deharveng & Gers, 1993 from a cave of Ratchaburi province in the absence of eyes, two rows of dental spines, labial basis chaetotaxy, similar dorsal chaetotaxy from head to Abd. IV, anterior ventral tube chaetotaxy, and claw morphology. It can be distinguished by the combination of characters listed in Tables 3A View Table 3A and 3B View Table 3B , in particular the absence of the chaetae “E” on head, larger size (1.3-1.5 vs. 0.95-1.3 mm), antennae relatively shorter (0.35-0.4 vs. 0.45-0.5 × as long as body), tenent hair acuminate vs. usually clavate, each lateral flap of ventral tube with six chaetae (vs. seven), dental spines of the internal row more numerous (30-37 vs. 19-23) and higher ratio of dens:mucro (12-15 vs. 9).

The pair of mac immediately ahead A and that ahead the uneven anterior mac on head are not figured in Deharveng and Gers (1993), as they were not considered as mac, but long mes. Their sockets in the new species are smaller than those of mac, but clearly marked.