Trichopeltis cavernicola, Golovatch, Sergei I., 2016

Golovatch, Sergei I., 2016, The millipede family Cryptodesmidae in Indochina (Diplopoda, Polydesmida), ZooKeys 578, pp. 33-43 : 34-36

Taxon classification Animalia Polydesmida Cryptodesmidae

Trichopeltis cavernicola sp. n. Figs 1-3, 4-7

Type material.

Holotype ♂ (MNHN JC 367), Laos, Khammouane Prov., Ban Naden, Cave Tham Namlat, N17.504969°, E105.385598°, ca 180 m a.s.l., 09.11.2011, leg. L. Deharveng & A. Bedos (Lao 11-51).

Name.

To emphasize the cavernicoly and troglomorphic appearance of this new species; noun in apposition.

Diagnosis.

Differs from congeners by the relatively gracile and slender body in which each midbody paratergite is clearly narrower than prozonite width, coupled with the increasingly upturned postcollum paraterga and such obviously troglomorphic features as an unpigmented body, as well as the extremely long and slender legs and antennae. In addition, much of the distolateral part of an indistinctly tripartite gonopod telopodite is densely covered with wart-shaped knobs while the tip of the solenomere is vestigial and simple.

Description.

Length ca 11 mm, width of midbody pro- and metazonae 0.8 and 1.7 mm, respectively. General coloration in alcohol entirely pallid, tegument mostly translucent (Figs 1-3).

Body with 20 segments (composed of collum plus 17 podous and one apodous rings, plus telson). In width, head << collum <segment 2 <3 <4-17; thereafter body rapidly tapering towards telson. Head behind labrum very densely and clearly microgranulate and pilose; epicranial suture superficial, more distinct in vertigial region. Antennae unusually long and slender for a cryptodesmid (Figs 2, 3), barely clavate, not placed inside a groove, in situ reaching behind segment 3 when stretched laterally or ventrolaterally; in length, antennomere 2> 5=6> 3=4; antennomeres 5 and 6 each with a compact apicodorsal group of bacilliform sensilla. Interantennal isthmus about as broad as diameter of antennal socket. Tegument dull, clearly microgranulate almost throughout, only prozonae usually more finely shagreened. Dorsum from only slightly and regularly convex to increasingly flat towards midbody metazonae; paraterga mostly set at about upper 1/4 of body, very strongly developed (Figs 1-3), beginning with collum. Collum completely covering the head from above, biconvex, but clearly lobulate anteriorly (10+10 lobulations) and caudolaterally (5+5 lobulations, including lateralmost one shared with anterior row), but not mediocaudally; paraterga distinctly upturned as opposed to subhorizontal paraterga 2-7. Postcollum paraterga short and narrowly rounded laterally, on each side usually with 3-4 lateral, 4-5 anterior and 4-5 posterior lobulations, gradually, but increasingly upturned and elevated above dorsum towards segment 19 (Figs 1-3). Marginal lobulations on paraterga mostly rounded, relatively large and well separated from one another, lateral end of paraterga drawn caudad gradually, but increasingly on segments 15-19, produced behind rear tergal margin only on segments 18 and 19. Caudal row of lobulations on paraterga gradually diminished in size towards paratergal base to get transformed into 5+5 clearly smaller, subequal, subhorizontal, caudomarginal lobules, each of the latter bearing a smaller, narrowly rounded, subvertical tubercle/knob at base. Another two, more or less regular, transverse rows of 6-8+6-8 similar, almost sharp, subvertical knobs extending onto paraterga in front of mediocaudal row until about segment 15, followed by three irregular rows of similar knobs thereafter (Fig. 1). As a result, middle parts of metaterga 2-14 with three, of following metaterga with four, transverse, usually rather irregular rows of small, round, setigerous knobs/tubercles in addition to caudalmost, regular row of smaller lobules just in front of a microspiculate limbus. Tergal setae long and simple, mostly abraded, only a few retained on several caudal metaterga (Fig. 1). Neither axial line nor radii, nor pleurosternal carinae. Ozopores invisible, pore formula untraceable. Stricture dividing pro- and metazonae broad, shallow and microgranulate like adjacent metazonae. Epiproct (Figs 1-3) short, conical, subtruncate at apex. Hypoproct (Fig. 3) subtrapeziform, 1+1 caudal setae clearly separated, borne on small knobs.

Sternites narrow (Fig. 3), sparsely setose, moderately impressed along main axis, clearly broadened only between coxae 7 and 9, respectively. Legs very long and slender, without modifications (Figs 1-4), ca 1.4-1.5 times as long as paratergal width (♂) (Figs 1-3); in length, femora = tarsi >> prefemora> coxae> postfemora and tibiae (Fig. 4); gonapophyses on coxae 2 small cones; neither adenostyles nor tarsal brushes. Gonopod aperture transversely ovoid, caudal and lateral margins thin, slightly elevated (Fig. 3).

Gonopods (Fig. 5-7) fairly complex, in situ held parallel to each other (Fig. 3). Telopodite only slightly curved caudad, vaguely tripartite. A short, simple, very sparsely setose, rounded lobe (lo) lying caudally at about midlength of telopodite and marking the end of the latter’s stout half. A twice as slender acropodite subdivided into an irregularly shaped lateral branch (b), longest, subunciform apically and densely beset with wart-like knobs on lateral face, and a rather simple, suberect, mesal solenomere branch (sl) apically extended into a small, mesal, densely setose lobule (n) with an adjacent, minute, simple, rod-shaped solenomere proper (t). Neither an accessory seminal chamber nor a hairy pulvillus.

Remarks.

Trichopeltis Pocock, 1894 (= Otodesmus Cook, 1896), formerly comprised six species that range from the Himalayas of India (Assam and Darjeeling District) and Myanmar to southern China, Indochina and Indonesia (Sumatra) ( Golovatch et al. 2010, Golovatch and Akkari 2016).

The new species is not only the first clearly troglomorphic Trichopeltis , but also the first presumed troglobite among the Asian Cryptodesmidae . Similarly strongly cave-adapted cryptodesmids are exceptional, e.g. the highly troglomorphic Peridontodesmella alba Schubart, 1957, from several caves in São Paulo State, Brazil ( Trajano et al. 2000).