Svaniulus waltheri Vagalinski, gen. nov., sp. nov.

Vagalinski, Boyan & Golovatch, Sergei I., 2021, The millipede tribe Brachyiulini in the Caucasus (Diplopoda, Julida, Julidae), ZooKeys 1058, pp. 1-127 : 1

Svaniulus waltheri Vagalinski, gen. nov., sp. nov.

Figs 50 , 51 , 52

Material examined

(SMNG): Holotype: ♂ (in head to pleurotergum 7 and rest of body, gonopods intact), Georgia: Samegrelo-Zemo Svaneti, Lebarde, Tekhuri Valley, 30 rkm from Taleri towards Lebarde [at the influx of Lebarde and Tekhuri rivers], 42.7258°N, 42.4703°E, 1260 m a.s.l., 10.X.2011, F. Walther leg. Paratypes: 1 ♂ (in 3 pieces, leg 7, mid-body and end-body leg, hypoproct, left flange of pleurotergum 7, and penis dissected, gonopods prepared for SEM), 1 ♀ (in head to body ring 3 and rest of body, vulvae dissected, right one prepared for SEM), same collecting data as of the holotype.

Diagnosis.

Differs from its only known congener, S. ryvkini gen. nov., sp. nov., mostly by being on average slightly larger, by the relatively more slender male antennae, by the position and shape of the ventral protrusions of male pleurotergum 7, and by the following details of gonopod structure: promere more slender, distally significantly narrowing, with the mesal process barely exceeding the apex, vs. the same being somewhat stouter, only apically abruptly narrowing, and with the mesal process significantly exceeding the apex in S. ryvkini gen. nov., sp. nov.; opisthomere lacking a distomesal process, vs. this being present in S. ryvkini gen. nov., sp. nov., having the basoposterior process with a distinct apical corner, vs. the same ending in a broad and flat margin in S. ryvkini gen. nov. sp. nov., and with the solenomere being somewhat enlarged apically, vs. the same narrowing all the way to the top in S. ryvkini gen. nov., sp. nov.

Name.

Honours Frank Walther, a malacologist and an active collector of various invertebrate groups, including the material used for the present description.

Description.

Measurements: holotype in S X, 43+1+T, L = 26 mm, H = 1.8 mm; paratype ♂ in S IX, 43+1+T, L = 27.5 mm, H = 1.75 mm; paratype ♀ in S IX, 44+1+T, L = 37.5 mm, H = 2.65 mm.

Colouration (apparently somewhat faded) (Fig. 50 ): Similar to S. ryvkini gen. nov., sp. nov., but generally lighter, predominantly grey rather than brown, without significant difference between dorsal and ventral sides, and without transverse dark stripes along pro-metazonal sutures; prozonae dark grey, with numerous, densely set, light brown-beige spots arranged transversely above and below ozopore level; metazonae mostly grey, with numerous, minute, dark brown/blackish dots throughout, dorsally with a very narrow, transverse, blurred, dark brown band in posterior section; hind margins ochre-brown.

External structures: Eye patches in adults vertically rather elongate, due to partial reduction of the higher developmental (vertical) rows, consisting of 21-35 markedly convex ommatidia. Vertigial, supralabral, and labral setae: two, four, and 16-18, respectively. Antennae (Fig. 50A ) 1.6-1.8 × as long as head in the males, and 1.25 × in the female; antennomere 2> 5 ≥ 3> 4> 6. Gnathochilarium as in S. ryvkini gen. nov., sp. nov., but lamellae linguales with three rather than four setae in a longitudinal row, and male stipites without setose hump.

Body rings slightly to moderately vaulted. Male hypoproct (Fig. 51A ) very similar to that in S. ryvkini gen. nov., sp. nov., but almost perfectly semi-circular and with a densely and bluntly serrate margin, rather than apically somewhat flattened and with only several faint undulations. Tarsus of mid-body legs subequal to, to slightly longer than, tibia, and ca. 3 × as long as apical claw.

Male sexual characters: Walking legs with adhesive pads still present in caudalmost pairs. Pleurotergum 7 ventrally forming rather narrow and oar-like lobes (Fig. 51B ) with a slightly concave apical margin, originating from border zone between pro- and metazona, protruding mostly ventrad behind gonopods. Penis (Fig. 51C ) similar to that in S. ryvkini gen. nov., sp. nov., but trapezoidal (widening distally) rather than barrel-shaped.

All other external somatic characters as in S. ryvkini gen. nov., sp. nov.

Gonopods (Figs 51D , 52 ): Promere (Fig. 52A ) similar to that in S. ryvkini gen. nov., sp. nov., but more slender, distally mostly symmetrical rather than with a markedly convex lateral margin; mesal process barely, rather than considerably, surpassing the apex of promere, and ending with a finer, less strongly bent tip; median and distal ridges less strongly pronounced compared to the type species. Opisthomere (Figs 51D , 52C-F ): lacking a distomesal process; basoposterior process narrower in comparison to S. ryvkini gen. nov., sp. nov., with a distinct apical corner rather than with a flat margin, and with a much smaller mesal lobe; mesal side with a slender lobe (presumably gonocoxal gland) and a rather deep and narrow anteromesal sinus; solenomere somewhat enlarged distally rather than narrowing; otherwise of a very similar shape to that of the type species.

Female sexual characters: First two leg pairs of same condition as in S. ryvkini gen. nov., sp. nov. Vulva (Fig. 51E ) externally also very similar to the type species, mainly differing in being more elongated and with the operculum being equal to, rather than slightly shorter than, bursa. Receptaculum seminis with a somewhat wider and shorter central tube, not forming a distinct ampulla at bottom; posterior tube gradually widening towards bottom, rather than constricting to form an ampulla.

Remark.

Despite the distance between the type localities of S. waltheri gen. nov., sp. nov. and S. ryvkini gen. nov., sp. nov. being only ca. 35 air-km, the distribution areas of the two species are probably divided by the Egrisi Mountain Range. With summit parts above 3000 m a.s.l., it could have split the population of the common ancestor of these two closely related species during colder periods in the geological past.

General distribution.

SWGC.

Figures

Figure 50. Svaniulus waltheri gen. nov., sp. nov., ♂ paratype A head and body rings 1 - 3 B telson, lateral views. Not to scale.

Figure 51. Svaniulus waltheri gen. nov., sp. nov., ♂ (A-D) and ♀ (E) paratypes A hypoproct, ventral view B right flange of pleurotergum 7, ventro-lateral view C penis, caudal view D right opisthomere, oral view E left vulva, latero-caudal view. Scale bars: 0.1 mm. Abbreviations: ct central tube, g (supposed) gonocoxal gland, ml mesomeroidal lobe, msl mesal lobe of basoposterior process, pt posterior tube, s solenomere, sp apical process of solenomere.

Figure 52. Svaniulus waltheri gen. nov., sp. nov., gonopods of ♂ paratype A right promere, caudal view B apical part of flagellum C right opisthomere, oral view D distal part of the same, latero-oral view E distal part of left opisthomere, caudo-mesal view F apical part of the same, meso-caudal view. Scale bars: 0.1 mm (A, C-E), 0.05 mm (F), 0.01 mm (B). Abbreviations: bpp basoposterior process, dr distal ridge, f flagellum, g (supposed) gonocoxal gland, ml mesomeroidal lobe, mp mesal process, mr median ridge, msl mesal lobe of basoposterior process, s solenomere, sf spiniform filaments, sp apical process of solenomere.