Klimakodesmus bilobocaudatus, Sudhikumar, 2021

Sudhikumar, Ambalaparambil Vasu, 2021, The millipede genus Klimakodesmus Carl, 1932, with the description of a new species from Kerala state, southern India (Diplopoda, Polydesmida, Pyrgodesmidae), Zootaxa 4980 (2), pp. 373-382 : 376-380

Klimakodesmus bilobocaudatus sp. nov.

Figs 1–15

Material examined. Adult male holotype (CATE-5302), 2 adult male and 6 subadult female paratypes (CATE- 5302B–CATE-5302I), 1 adult male and 2 subadult female paratypes ( ZMUM), India, Kerala state, Kannur district, N11°58’2.5”, E75°17’46.6”, 5 m a.s.l., 27/01/2021, M.D. Aswathy leg.

Name. To emphasize a caudally relatively deeply bilobed dorsal keel ( PM) on ring 19 in the new species; adjective.

Diagnosis. The new species differs clearly from K. gravelyi , the only other congener to be accepted ( Carl 1932), by the more regularly tuberculate collum (cf. Figs 5 and 16 ), the lower PM and DL which are mostly inclined caudad (vs. inclined forward until ring 16, cf. Figs 7 , 8 and 17 ), the caudally more deeply bilobed dorsal keel (PM) on ring 19 (vs. indistinctly bilobulate, cf. Figs 9, 10 and 18 ), the laterally bi- (rings 3 and 4) or trilobate (remaining postcollum rings) paraterga (vs. mostly bilobate, trilobate only on ring 2, cf. Figs 5 , 8, 9 and 17–19 ), and the gonopods showing subspherical coxites (vs. squarish) and subcontiguous, apically subunciform and crossing each other (vs. divergent and suberect) telopodites, each of the latter additionally reinforced with a mesobasally thickened wall (vs. a laterobasal lobe, cf. Figs 12–15 and 20 & 21 ).

Description. Length ca. 3.68 mm, width of midbody segments 0.10 and 0.14 mm on pro- and metazonae, respectively (holotype). Length of adult male paratypes ca. 3.0– 3.8 mm, that of subadult female paratypes 3.2–3.5 mm. Width of adult male paratypes ca. 0.40–0.45 mm, that of subadult female paratypes 0.44–0.48 mm. Live colouration generally pink; antennae, legs and venter translucent, lighter than dorsum ( Figs 1 , 7 & 9 ). Colouration in alcohol after 2 months of preservation pale brown to pinkish brown, legs and antennae faded to translucent ( Figs 2–6 , 8 & 10 ). No earth crust visible on body.

Most characters as in the generic description above, except as follows.

Body with 20 segments (likely in both sexes, see below) ( Figs 2 & 4 ). In width, head << collum <segment 2=3 <4–6 <7–9 <10–15, body gradually tapering towards telson thereafter. Head circular, labral region moderately setose, epicranial suture rather deep, vertex microgranulate ( Fig. 6 ). Interantennal isthmus nearly as wide as diameter of antennal socket. Antennae short, weakly clavate, in situ reaching body segment/ring 3 when stretched ventrolaterally. In length, antennomere 7<3<1<6<4<2<<5; antennomeres 5–7 each with a more or less compact apicodorsal group of bacilliform sensilla ( Figs 6 & 7 ). Collum flabellate, completely covering the head from above; anterior margin with 5+5 distinct, equal, moderately incised and rounded lobulations; central part domed, with 2+2 and 3+3 prominent and rounded tubercles arranged in two transverse rows ( Figs 2–7 ). Paraterga set low (at about half of midbody height), subhorizontal to faintly declivous. Dorsum strongly arched, its outline smoothly extending onto paraterga ( Figs 3 & 7 ). Prozonae, as well as deep and thin strictures between pro- and metazonae finely alveolate. Postcollum metaterga with strongly differentiated dorsal tuberculations: 2+2 longitudinal crests/rows of mostly 2+2 fused tubercles, those before ring 19 slightly inclined caudad, but PM on ring 19 abruptly modified into a mid-dorsal, strongly elongate, conspicuous and caudally clearly bilobate ridge overhanging and concealing a short epiproct ( Figs 2–4 , 8–10 ). Paraterga broad, thin, rather irregularly tuberculate near bases and clearly lobulated laterally, with three rounded and moderately incised lobulations on rings 2–19, regardless of cylindrical porosteles located between the 2 nd and 3 rd lobulations on rings 5, 7, 9, 10, 12, 13, 15 and 16 ( Figs 2–10 ); only paraterga 3 and 4 with last lobulation in a clearly caudolateral position ( Figs 5–7 ). Epiproct ( Fig. 10 ) finger-shaped, tip bent down and divided into two round bulbs. Hypoproct ( Fig. 10 ) semi-circular, with 1+1 strong setae borne on minute, caudal, paramedian knobs.

Legs with neither adenostyles nor tarsal brushes ( Fig. 11 ). In length, tarsi> femora> prefemora> tibiae> coxae> postfemora; claws simple, slightly curved ventrally.

Gonopods ( Figs 12–15 ) relatively simple, placed inside a transversely oblong-oval gonopodal aperture, the latter with thin and slightly elevated caudal and lateral margins; in situ, both gonopods strongly exposed, held mostly parallel to one another, with only tips crossing each other. Coxites (cx) voluminous, but moderately enlarged, gonocoel thus being relatively shallow; cannulae simple. Telopodites directed caudally, each unipartite and subtriangular, long and slender, gradually attenuating distad and acuminate apically, each represented solely by a solenomere (sl) and supporting a seminal groove running along lateral margin to the end of a laterally directed and unciform apical part, and additionally reinforced basally through a distinctly thickened caudomesal wall of a prominent, membranous, mesal lobe (lo); prefemorite as usual, relatively short, densely and strongly setose.

Ecological notes. This new species was found under rotting wood near a lowland swamp overgrown with Myristica forest in the Kannur district, northern Kerala, India. The habitat area of approximately 20 ha is a sacred grove protected by local people. In contrast, K. gravelyi came from high-altitude areas (1000–1600 m a.s.l.) in the state of Tamil Nadu ( Carl 1932), Western Ghats, southern India ( Fig. 22 ).

It seems noteworthy that all females collected at the type locality in January appear to be subadults, each with 19 body segments. This has been proven by dissecting the vulvae which have always been found underdeveloped (amorphous ovoid clods devoid of setae), and an anterior, ventral, transverse, marginal ridge on ring 3 missing. This agrees well with the common wisdom that only adult males in Polydesmida , but never adult females, can be composed of a lesser number of body rings. Usually, in the course of teloanamorphosis characteristic of the order Polydesmida , both the males and females of Polydesmida show the same number of body rings, either 20 or 19, more rarely 18, exceptionally up to 40 ( Shear et al. 2016). When there is a difference in polydesmidan body segment counts, the adult males typically have one segment less and nearly always remain stable per sex ( Enghoff et al. 2015). Only exceptionally, as is the case of Ammodesmus granum Cook, 1896 and A. congoensis VandenSpiegel & Golovatch, 2015 (Ammodesmidae) , from western or central Africa, respectively, can both sexes vary in the number (18 or 19) of body rings ( VandenSpiegel & Golovatch 2012, 2015).

In Klimakodesmus species , however, the situation is ordinary, as both sexes (must) equally have 20 body segments. The absence of adult females in the type series seems best to be accounted for by seasonal factors alone.

Figures

FIGURE 22. Distribution of the genus Klimakodesmus: K. gravelyi in Tamil Nadu state (orange dots), and K. bilobocaudatus sp. nov. in Kerala state (red dot).

FIGURES 1–4. Klimakodesmus bilobocaudatus sp. nov. 1. Natural microhabitat (rotting wood with a colony on the surface, photographed not to scale). 2. Adult male paratype, dorsal view. 3. Subadult female paratype, lateral view. 4. Adult male paratype, ventral view.

FIGURES 5–7. Klimakodesmus bilobocaudatus sp. nov. Anterior parts of body, dorsal, ventral and lateral views, respectively.

FIGURES 8–15. Klimakodesmus bilobocaudatus sp. nov. 8. Posterior half of body (subadult female paratype), lateral view. 9 & 10. Posterior part of body (adult male paratype), dorsal and ventral views, respectively. 11. Midbody leg (adult male paratype), lateral view. 12–14. Both gonopods (adult male paratype), caudal, oral and caudal views, respectively. 15. Right gonopod, caudal view. Abbreviations: cx, coxite; lo, mesal lobe; sl, solenomere. NB: Figures 14 & 15 drawn not to scale.

FIGURES 16–21. Klimakodesmus gravelyi Carl, 1932, male holotype, after Carl (1932). 16. Collum, dorsal view. 17. Anterior part of body, lateral view. 18 & 19. Posterior part of body, dorsal and lateral views, respectively. 20 & 21. Left and right gonopods, caudal and oral views, respectively. Abbreviations: cx, coxite; lo, lateral lobe; sl, solenomere. Drawn not to scale.