Omobrachyiulus zuevi Vagalinski, 2021

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

Omobrachyiulus zuevi Vagalinski sp. nov.

Figs 35 , 36 , 37

Material examined

(ZMUM). Holotype: ♂ (in head to ring 6 and rest of body, opisthomeres dissected), Stavropol , Mamayskiy Forest, 31.III.2013, R. Zuev leg. Paratypes: 1 ♂ (in head to ring 2, ring 3 to ring 6, pleurotergum 7 (broken into two pieces), and rest of body; penis and pleurotergum 7 dissected, gonopods prepared for SEM), 1 ♀ (in head to body ring 2 + rest of body, left vulva dissected), same collecting data as for holotype .

Diagnosis.

A species of Omobrachyiulus being morphologically very similar to O. roseni (Verhoeff, 1921). Differing from the latter species by having generally stouter, more robust gonopods, and by details of the opisthomere, as follows: anterior process minute, vestigial, mostly hidden between base of solenomere and distal part of mesomeroidal lobe, vs. the same being significantly larger, clearly visible from most angles in O. roseni ; mesomeroidal lobe protruding in a massive, rounded, apicolateral part, and a much smaller mesoapical part, vs. the apicolateral part being much less pronounced, nearly same size as the mesoapical one in O. roseni ; solenomere with a strongly enlarged, flower-like apex, vs. the same being apically only moderately enlarged, with a soft sigmoid process directed basad in O. roseni .

Name.

Honours Roman Zuev, a myriapodologist from Stavropol, Russia, and the collector of the material on which the description of this new species is based.

Description.

Measurements: holotype ♂ in S VIII or IX, 40+2+T, L = 10.5 mm, H = 0.8 mm; paratype ♂ in S VIII or IX, 42+2+T, L = 12 mm, H = 0.85 mm; paratype ♀ in S IX or X, 44+1+T, L = 14.5 mm, H = 1.15 mm.

Colouration (Fig. 35 ): Mostly brown-beige, frontal and caudal parts of body darker than mid-body; head with the usual pattern; antennae light brown; collum dark brown at margins; prozonae with numerous densely set yellowish oval spots surrounded by brown rings forming a reticulate pattern; dorsally with a transverse dark brown stripe; metazonae light brown to yellowish beige; whole ventral side of body light beige; dorsum with a dark brown axial line; legs very light, in males dorsally with brown tinges.

External structures: Eye patches in adults consisting of ca. 30 weakly pronounced ommatidia, arranged in hardly recognisable vertical rows. Vertigial, supralabral, and labral setae: two, four, and 13 or 14, respectively. Antennae (in Fig. 35A, B ) ca. 1.3 × as long as head in males and 1.15 × in females; antennomere 2> 3 = 5> 4> 6. Gnathochilarium with relatively small promentum separating lamellae linguales in ca. 1/3 of their length, each latter with four setae in a longitudinal row. Collum mostly smooth, with only three or four very shallow, barely visible grooves near posterolateral corners.

Body rings not vaulted. Prozonae with very short and fine, mostly parallel longitudinal striae. Metazonae rather shallowly striated, n Schub = 6 or 7; setae absent. Ozopores set tightly behind pro-metazonal suture in more anterior rings, gradually moved further back, to nearly equal to their dm behind the suture in caudalmost rings, sutures slightly (in the males) to strongly (in the female) sinuous in front of ozopores in anterior body section. Tarsus of mid-body legs as long as tibia, and slightly> 3 × as long as apical claw.

Telson (Fig. 35C ): Epiproct moderately long, stout, turned somewhat ventrad in males, almost perfectly straight in females, ending with a short and blunt hyaline tip, not reaching the level of the longest paraproctal setae; with several long setae. Hypoproct semi-elliptical (more broadly rounded in the female) ventrally with two median submarginal setae, margin somewhat protruding behind rear contour of paraprocts in the males, tightly adhering to their ventral side in the female. Paraprocts sparsely covered with very long setae; no distinct rows of shorter setae along caudal margins.

Male sexual characters: Mandibular stipites (in Fig. 35A ) moderately expanded, protruding mostly ventrad, forming a rounded anteroventral corner. Leg pair 1 compact hooks turned slightly to considerably against one another. Leg pair 2 and following pairs with crested adhesive pads, postfemoral ones disappearing after mid-body, tibial ones present until caudalmost legs; femora of leg pair 3 and next several pairs with an oval groove. Pleurotergum 7 ventrally forming elongated rounded lobes (Fig. 36A ) originating from the zone around pro-metazonal suture, protruding mostly mesad behind gonopods. Penis (Fig. 36B, C ) compact, stout, broader than long, with very short, contiguous, apical lobes ending in small terminal lamellae turned caudad.

Gonopods (Figs 36D , 37 ): Promere (Fig. 37A ) relatively broad and stout, as high as opisthomere, broadest at base, somewhat narrowing in mid-section, then widening again distally, before lateral margin abruptly slanting to join mesal margin in a narrow, blunt apex; caudal surface with a well-pronounced, strongly arched, median ridge, a relatively deep and very narrow median groove, and a broad and deep distal groove; a broad and flat, subapical denticle turned basocaudad; flagellum somewhat longer than height of promere. Opisthomere (Figs 36D , 37B-E ) stout and robust; basoposterior process present as a weakly pronounced lobe, distally forming a broad, flattened, shield-like, apical outgrowth protruding in a median, blunt, digitiform tip at margin; anterior process very small, mostly concealed behind distal part of mesomeroidal lobe, the latter massive, very strongly pronounced, distally extending into a broad and rounded apicolateral part, and a much lower, pointed, pyramidal apicomesal part; mesal side with a rather narrow lobe (presumably gonocoxal gland), and a very deep and spacious anteromesal sinus; a row of long and erect spiniform filaments at proximal section of flagellum channel; solenomere unipartite, rather broad tubular, turned anteriad, apically strongly broadening, forming a lamellar flower-like structure with multiple, minute, spiniform filaments at margin.

Female sexual characters: Leg pairs 1 and 2 slightly thicker than following legs. Vulva (Fig. 36E ) symmetrical, relatively elongate, somewhat compressed on sides; bursa with a strongly obtuse postero-apical margin; operculum as high as bursa, both parts ending with small hyaline protrusions; setation dense throughout. Receptaculum seminis consisting of a rather broad, digitiform, central tube, and a very narrow, short, mostly straight, posterior tube gradually widening into a small, drop-like, posterior ampulla.

Remark.

The complete lack of metazonal setae is a rare condition to be observed in the Brachyiulini : apart from O. zuevi sp. nov. and its close sibling, O. roseni , this can only be seen in their Aegean congener, O. strasseri Vagalinski & Lazányi, 2018.

General distribution.

WCIS.

The Opisthomere sevangensis group

Characterisation. Both gonopod pairs subequal in height. Promere lacking a distinct distal groove. Opisthomere rather elongated, with a moderately to strongly pronounced mesomeroidal lobe developed mostly or entirely within the basalmost part of the opisthomere, a basoposterior process with variously pronounced proximal part, ending with a narrow, more or less tapering apical outgrowth turned partly to completely anteriad, a well-developed, ridge-like, at least partly lamellar, anterior process, a variously developed anteromesal sinus, a flagellum channel overgrown with rather short and slanting spiniform filaments, and a more or less slender, uni- or bipartite solenomere directed (almost) completely distad. Vulva with the operculum considerably higher than the bursa.

Included species.

O. sevangensis (Lohmander, 1932), comb. nov.

O. kvavadzei Vagalinski, sp. nov.

O. ponticus Vagalinski, sp. nov.

O. trochiloides Vagalinski, sp. nov.

Figures

Figure 35. Omobrachyiulus zuevi sp. nov., ♂ holotype (A, C) and ♀ paratype (B) A head and body rings 1 - 5, lateral view B head and collum, dorsolateral view C telson, lateral view. Not to scale.

Figure 36. Omobrachyiulus zuevi sp. nov., ♂ (A-D) and ♀ (E) paratypes A left flange of pleurotergum 7, ventro-lateral view B penis, caudal view C same, lateral view D right opisthomere, oral-mesal view E left vulva, caudal, somewhat lateral view. Scale bars: 0.2 mm. Abbreviations: ao apical outgrowth of basoposterior process, bpp basoposterior process, ct central tube, ml mesomeroidal lobe, pa posterior ampulla, pt posterior tube, s solenomere, sf spiniform filaments.

Figure 37. Omobrachyiulus zuevi sp. nov., gonopods of ♂ paratype A right promere, caudal view B right opisthomere, mesal, somewhat oral view C left opisthomere, lateral, somewhat oral view D distal part of right opisthomere, oral-mesal view E apex of solenomere, same aspect. Scale bars: 0.1 mm (A-C), 0.05 mm (D), 0.01 mm (E). Abbreviations: al apicolateral part of mesomeroidal lobe, am apicomesal part of mesomeroidal lobe, ao apical outgrowth of basoposterior process, ap anterior process bpp basoposterior process, d subapical denticle dg distal groove f flagellum, fc flagellum channel, g (supposed) gonocoxal gland, mg median groove ml mesomeroidal lobe, mr median ridge, s solenomere, sf spiniform filaments, si anteromesal sinus.