Omobrachyiulus pristi s 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 pristi s Vagalinski sp. nov.

Figs 21 , 22 , 23

Material examined

(all from Georgia). Holotype: ♂ (unbroken) (ZMUM), AR Ajara, 15 km W of Adigeni , Abies , Picea , Fagus , Acer , etc., 1500-1700 m, litter, logs, under stones, 14-15.V.1983 , SIG leg. Paratypes: 1 ♂ (ZMUM) (in head and 4 pieces, gonopods, penis, legs 2, 3, 7 and a mid-body leg dissected), 1 ♂ (NHMD) (unbroken), 1 ♂ (NMNHS) (unbroken), 2 ♀♀ (ZMUM) (one unbroken, the other in 3 pieces with dissected left vulva), 1 ♀ (NHMD) (unbroken), 1 ♀ (NMNHS) (unbroken), 1 subad. ♀ (ZMUM) (unbroken), 5 juv. (ZMUM) (two unbroken, the others fragmented), same collecting data as for holotype ; 1 ♂ (ZMUM) (in 3 pieces, gonopods prepared for SEM), AR Ajara, Khulo Distr., 1800 m a.s.l., Danisparauli , Abies and fern litter, 10.X.1981 , SIG leg.; 1 ♂ (ZMUM) (in 5 pieces, with dissected gonopods), 2 ♀♀ (ZMUM) (one in 2 pieces, the other unbroken), AR Ajara, Khulo Distr., Goderdzi Pass , 2000 m, sparse Abies and Picea forest, litter, under stones and in rotten logs, 10.X.1981 , SIG leg.; 3 ♂♂ (SMNG) (two in 2 pieces with dissected gonopods, one unbroken), 1 ♂ (IBER) (in head to ring 6, pleurotergum 7 to ring 9, and rest of body, gonopods dissected), 3 ♀♀ (SMNG) (all unbroken), 1 ♀ (IBER) (unbroken), 1 juv., one head to ring 6 ♂ fragment (SMNG), Sairme Gorge , 41.9580°N, 42.7713°E, 600 m a.s.l., Fagus orientalis and Castanea sativa , in litter, 14.VII.2013, L. Mumladze leg. ; 3 ♂♂ (SMNG) (one unbroken, one in 2 pieces with intact gonopods, one in 3 pieces with dissected gonopods), Sairme Gorge , 41.8468°N, 42.8075°E, 2200 m a.s.l., Acer sp. and Betula sp., 11.VII.2013, L. Mumladze leg.

Diagnosis.

A species of Omobrachyiulus most clearly differing from congeners by the caudally flattened, serrate, elongated, apical outgrowth of the basoposterior process of opisthomere, and by the conspicuously large anterior process which is almost as high as the solenomere.

Name.

To emphasise the caudally flattened, serrate, apical outgrowth of the basoposterior process of opisthomere, resembling the rostrum in the sawfishes of the family Pristidae when observed from caudal or caudomesal view. Noun in apposition.

Description.

Measurements: holotype ♂ in S IX, 41+1+T, L = 15 mm, H = 1.3 mm; paratype ♂♂ in S IX-X, 41-44+1+T, L = 15-17 mm, H = 1.25-1.4 mm; paratype ♀♀ in S IX-X, 38-42+1-2+T, L = 15-19 mm, H = 1.4-1.65 mm.

Colouration (considerably faded from ethanol) (Fig. 21 ): Prozonae dorsolaterally dark grey to blackish, ventrolaterally dark grey near pro-metazonal suture; metazonae dorsolaterally with a transverse dark brown stripe; ozopores surrounded by an irregular blackish spot; ventrolateral side of body mostly light brown-beige; dorsum with a black axial line.

External structures: Eye patches in adults consisting of 30-35 ommatidia, mostly arranged in easily countable vertical rows. Vertigial, supralabral, and labral setae: two, four, and 22-26, respectively. Antennae (in Fig. 21B ) 1.40-1.55 × as long as head in males and 1.25-1.45 × in females; antennomere 2> 3 = 5> 4> 6. Gnathochilarium with a relatively small promentum separating lamellae linguales by <1/3 of their length, each latter with five setae in a longitudinal row; stipites in males basally with a kidney-shaped swelling densely covered with fine and stiff setae. Collum mostly smooth, with only several very short and fine striae near posterolateral corner.

Body rings somewhat vaulted (more significantly in caudal part of body). Prozonae with very short and fine longitudinal striae in their hind sections. Metazonae rather shallowly striated, n Schub = 8 or 9 in males and 11 or 12 in females; metazonal setae 2/5-1/2 of metazonal length. Ozopores set tightly behind pro-metazonal suture in more anterior rings, gradually moved further back, to nearly equal to their diameter behind the suture in caudalmost rings, sutures not sinuous in front of ozopores. Tarsus of mid-body legs 1.1-1.2 as long as tibia and ca. 4 × as long as apical claw.

Telson (in Fig. 21C ): Epiproct long (reaching the level of longest paraproctal setae), straight or slightly bent dorsad, ending with a minute hyaline tip. Hypoproct broadly rounded, ventrally with two median submarginal setae; barely protruding behind rear contour of paraprocts in males, tightly adhering to their ventral side in females. Paraprocts sparsely to moderately densely covered with long setae; no distinct rows of shorter setae along caudal margins.

Male sexual characters: Mandibular stipites (in Fig. 21B ) considerably expanded, broadly rounded, protruding mostly ventrad, with either an indistinct or strongly obtuse and blunt ventro-anterior corner. Leg pair 1 compact hooks, slightly to considerably turned against one another. Leg pair 2 slightly thicker than following legs, with a weakly pronounced adhesive pad distoventrally on tibia, without pad on postfemur; following pairs with two pads, one each on postfemur and tibia, both clearly discernible until caudalmost pairs; femora without modifications. Pleurotergum 7 strongly enlarged, ventrally forming rather slender, fingertip-shaped lobes (Fig. 22A ) originating entirely from metazona, protruding ventrad behind gonopods. Penis (Fig. 22B ) somewhat longer than broad, with very short, barely discernible apical lobes, and with broad, triangular, terminal lamellae directed completely caudad.

Gonopods (Figs 22C , 23 ): In situ considerably protruding from gonopodal sinus. Promere (Fig. 23B, p in Fig. 23A ) considerably higher than opisthomere, relatively slender; mesal margin more or less straight, lateral margin gently sinuous, distally both margins symmetrically slanting towards a narrowly rounded apex; caudal surface with a rather short, strongly pronounced, median ridge, a relatively deep and broad median groove, a broad distal groove, and a small, rounded, micro-squamous, distolateral lobe; flagellum somewhat longer than height of promere, distally with rows of blunt teeth directed basad. Opisthomere (Figs 22C , 23A, C-E ) relatively elongated; basoposterior process shaped like a weakly pronounced lobe, distally forming a rather narrow apical outgrowth with a flat caudal surface and densely serrate/dentate margins; anterior process large, distally tapering, bent caudad, reaching just below tip of solenomere; mesomeroidal lobe broad and rounded, weakly pronounced, positioned slightly above opisthomeral mid-height, forming a slender apicolateral part reaching as high as anterior process, proximally fused to the latter; lateral side with a rounded hump-like lobe; mesal side with a broad and flattened lobe (presumably gonocoxal gland), and a rather deep and spacious anteromesal sinus; a group of very long, erect, spiniform filaments at proximal section of flagellum channel; solenomere unipartite, tubular, relatively narrow, bent caudad, meso-apically with a fine digitiform process.

Female sexual characters: Leg pairs 1 and 2 markedly thicker, first also shorter, than following legs. Vulva (Fig. 22D ) mostly symmetrical, elongated, considerably compressed on sides; bursa with a strongly obtuse postero-apical margin; operculum slightly shorter than bursa, both parts ending with small hyaline protrusions; setation dense throughout. Receptaculum seminis consisting of a rather narrow, mostly straight, central tube, abruptly arched posteriad right before junction with a large, oblong, central ampulla, and a very narrow, somewhat folded, posterior tube leading to a rather large, pyriform, posterior ampulla.

Remark.

This species possesses some peculiar morphological characters, being the only representative of Omobrachyiulus that shows a vulval seminal receptaculum with a differentiated central ampulla, as well as the only one that lacks postfemoral adhesive pads on male leg pair 2.

General distribution.

LECA.

The Opisthomere implicitus group

Characterisation. Both gonopod pairs subequal in height. Promere possessing a distinct distal groove. Opisthomere rather slender, with a weakly to moderately pronounced mesomeroidal lobe, a basoposterior process with a weakly developed proximal part in the shape of a lamellar ridge, ending with a broad, collar-like, apical outgrowth showing a soft mesal part, a vestigial (if present) anterior process in the shape of an indistinct ridge, a narrow and not too deep anteromesal sinus, a flagellum channel overgrown with sparse, short to moderately long, spiniform filaments, and a slender, tubular, unipartite or distally branched solenomere directed mostly distad. Vulva with operculum shorter than, to subequal to, bursa.

Included species.

O. implicitus (Lohmander, 1936)

O. fasciatus Vagalinski, sp. nov.

O. lazanyiae Vagalinski, sp. nov.

Figures

Figure 21. Omobrachyiulus pristis sp. nov., ♂ holotype A habitus B head and body rings 1 - 4 C telson, lateral views. Not to scale.

Figure 22. Omobrachyiulus pristis sp. nov., ♂ (A-C) and ♀ (D) paratypes from near Adigeni, AR Ajara, Georgia (ZMUM) A right flange of pleurotergum 7, ventro-lateral view B penis, caudal view C distal part of left opisthomere, caudo-mesal view D left vulva, caudo-lateral view. Scale bars: 0.1 mm (A, D), 0.06 mm (C), 0.05 mm (B). Abbreviations: ao apical outgrowth of basoposterior process, ap anterior process, ca central ampulla, ct central tube, pa posterior ampulla, pt posterior tube, s solenomere.

Figure 23. Omobrachyiulus pristis sp. nov., gonopods of ♂ paratypes from Adigeni (A) and Danisparauli (B-E), AR Ajara, Georgia (ZMUM) A right gonopods, mesal view B right promere, caudal view C right opisthomere (with flagellum in its channel), caudo-mesal view D right opisthomere, lateral view E distal part of the same aspect. Scale bars: 0.1 mm (A-D), 0.05 mm (E). Abbreviations: al apicolateral part of mesomeroidal lobe, ao apical outgrowth of basoposterior process, ap anterior process, bpp basoposterior process, dg distal groove, dl distolateral lobe, f flagellum (broken near base), fc flagellum channel, g (supposed) gonocoxal gland, lp lateral lobe, mg median groove, ml mesomeroidal lobe, mr median ridge, p promere, s solenomere, sc seminal channel, sf spiniform filaments, si anteromesal sinus.