Tomocerus ( s. str. ) sikkimensis Mandal, Kumari & Mandal, 2024

Tomocerus ( s. str.) sikkimensis Mandal, Kumari & Mandal View in CoL sp. nov. ( Figs 1–5, Table 1)

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Materials examined. Holotype: 1 ♀ on slide, INDIA, Sikkim, Gangtok district, Lachen , 27°42'34"N, 88°33'43"E, 3248 m a.s.l., 9.ix.2022, G. P. Mandal leg., Reg. no– 3399/H14 GoogleMaps . Paratypes: 1 ♀ on slide, 12 specimens in alcohol, same data as holotype. Reg. no– 3585/H14; all materials are deposited at NZC, ZSI GoogleMaps .

Etymology. The species name is given on its collection state name.

Description. Average adult body length about 4.1 mm (without appendages). Body with brown scales, Ant. I–II all over-scaled, no scales on Ant. III–IV. Ant. III–IV with distinct annulations.

Colouration. ( Fig. 1A–B) Body ground colour pale yellow/gray, anterior part of the mouth with purple pigmentation. Ant. I–II distally with a slight purple patch; pigment gradually darker from Ant. III–IV. Eyes in dark purple patches. Diffuse pigment patches present in lateral side of head and abdomen; legs coloured up to claw.

Head. Head with 6+6 eyes, PAO absent. Antennae: Cephalic diagonal ratio= 3.3: 1. Ant. I: II: III: IV ratio as 1:1.7:9.7:2.7. Cephalic dorsal macrochaetotaxy as Fig. 2A, anterior area each side 3, 3; interocular area each side 2, 4; post ocular area 2+2; posterior area 2+2. Posterior margin with numerous small chaetae. Labral formula 4/5, 5, 4; Md. with four apical and five basal teeth. Mx. general type ( Fig. 2C) Outer lobe of maxillary palp with 1 large, 1 median and 2 small basal chaetae ( Fig. 2D). Lateral process of labial palp not reaching the base. Thorax. Th. II bordered with a row of dense mac and few antero-lateral mac. Five central mac arranged in a triangle on Th. II (a2, m2, m3, m4, a5) and two bothriotricha (m6, a6) present on each side. 3+3 posterior mac present on both Th. II (p2–p4) and Th. III (p1, p3, p5) ( Fig. 2B). Trochantero-femoral organ with 1, 1 slender chaeta. Ventral strong chaetae formula of Tita. I–III as 6–7, 5, 6–7. Unguis slender with baso-internal ridging visible, pointed paired lateral teeth present. Inner edge of unguis with basal tooth and 6 inner distal teeth, distal ones smaller. Unguiculus lanceolate with a single inner tooth. Tenent hair strong, clavate and slightly longer than inner edge of unguis; base of unguis with two-minute accessory chaetae; two thin and long guard chaetae ( Figs 2E, 4A). Abdomen. Pattern of body chaetotaxy as in Fig. 2B. Two median mac on Abd III (m3, m6) and Abd. IV with one medio-lateral mac (m6). Abd. I–V posterior row mac formula- 3 (m2–m4), 3 (m2–m4), 4 (p1, p3, p6, p7), 2 (p6, p7), 4 (m2, m3, m5, m6). Abd.VI with numerous moderate-size chaetae, most of them on the lateral and posterior side. Formula of midline pseudopores of terga as 1, 1, 1, 1, 0, 0. Abd. III and Abd. IV with one and two bothriotricha respectively. Ventral tube scaled with numerous posterior and 57–60 lateral flap chaetae ( Fig. 3A). Rami of tenaculum with 4+4 teeth, anterior face of corpus with 5 chaetae ( Fig. 3B). Ratio of manubrium: dens: mucro 3.5: 4.2: 1. Manubrium ventrally scaled, lateral side with 10–11 strong spinous chaetae ( Fig. 3C). Dental spines with numerous denticles, total 19 spines arranged as 2, 5, 5/ 5(6), II ( Figs 4B, 5A–B); proximal part with three distinct rows ( Figs 4C, 5C). Mucro elongated with paired basal and 4 intermediate teeth; numerous smooth chaetae with elongated sockets present ( Figs 4D, 5D).

Remarks. Tomocerous ( s. str.) sikkimensis sp. nov. is characterised by the presence of three rows of proximal dental spines and two large distal dental spines, 4 mucronal teeth, scaled ventral tube, 6 unguis teeth, this species is closely related to the species Tomocerus ( s. str.) conagensis Sun, Liang & Huang, 2006 . The new species also has a similarity with T. ( s. str.) nepalicus Yosii, 1971 in dental basal spine arrangement but dissimilar in mucro teeth number. Details of other differential characters of the new species with other related species are reflected in Table 1.