Omobrachyiulus trochiloides 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 trochiloides Vagalinski sp. nov.

Figs 44 , 45 , 46

Material examined.

Holotype: ♂ (in head to ring 6, pleurotergum 7, and rest of body; distal part of left antenna broken off, gonopods and right flange of pleurotergum 7 on permanent slide) (ZMUM), Georgia, Borjomi Nature Reserve , Baniskhevi Valley, 800-900 m, Picea , Fagus and Carpinus forest, in litter, logs and under stones, 12 and 16.V.1983, SIG leg . Paratypes: 1 ♂ (in head to ring 2, ring 3 to ring 6, and rest of body; gonopods prepared for SEM, penis, leg pair 2, leg 11 and mid-body leg on permanent slide) (ZMUM), 4 adult ♀♀ (one in head to ring 3 + rest of body, left vulva dissected) (ZMUM), 2 subadult ♀♀ (ZMUM), same collecting data as of the holotype; 1 ♂ (in head, collum to ring 6, pleurotergum 7 (in pieces), and ring 8 to rest of body; right antenna, leg pair 1, left flange of pleurotergum 7, and a mid-body leg dissected) (NMNHS), 1 adult and 2 subadult ♀♀ (unbroken) (NMNHS), Georgia, Chokhatauri District , near Bakhmaro, 4 km SSE Nabeglavi, 1950-2020 m, Abies nordmanniana , 8.VI.1981, SIG and J. Martens leg.

Diagnosis.

A species of Omobrachyiulus most simillar to O. sevangensis comb. nov., O. kvavadzei sp. nov., and O. ponticus sp. nov. in gonopod structure, as well as in the shape of the male telson. Easily distinguishable from all these species by the massive, well-differentiated basoposterior process of the opisthomere, ending with a very fine and slender apical outgrowth, as well as by the solenomere being unipartite rather than bifurcated apically.

Name.

Derived from the resemblance of the apical outgrowth of the basoposterior process of the opisthomere to the beak of a hummingbird, family Trochilidae . Adjective.

Description.

Measurements: male holotype in S VIII, 39+2+T, L = 17.5 mm, H = 1.1 mm; male paratypes in S VIII, 37+2+T, L = 12.8 mm, H = 1 mm, and 42+2+T, L = 18 mm, H = 1.2 mm; adult female paratypes in S IX-X, 40-46+0-1+T; L = 21-24 mm, H = 1.4-1.95 mm; subadult female paratypes in S VIII, 36-42+2+T.

Colouration (after> 35 years in alcohol) (Fig. 44 ): Head brown with a broad, dark band between ommatidia; collum brown, with a much darker frontal quarter and a dark posterior margin; frontal parts of prozonae light grey to creamy, posterior parts dark grey with some brownish spots; frontal parts of metazonae dark brown, posteriorly light ochre-brown; whole ventral side of body light brownish beige, each prozona ventrolaterally with a large, darker, blurred spot; paraprocts brown-grey, lighter caudally; dorsum with a black axial line; legs yellowish, tibiae and tarsi in males brown.

External structures: Eye patches in adults consisting of 28-35 ommatidia arranged in easily recognisable vertical rows. Vertigial, supralabral and labral setae: two, four, and 17-20, respectively. Antennae ca. 1.6 × as long as head in males and 1.2 × in females; antennomere 2> 3 ~ 5> 4> 6. Gnathochilarium with a promentum separating lamellae linguales in their proximal 2/5, the latter with three or four setae in a longitudinal row; stipites with a group of short, stiff setae basomedially near the borders with the lamellae. Collum mostly smooth, with four or five very short and shallow striae at posterolateral corners.

Body rings weakly vaulted. Prozonae with scattered minute grooves. Metazonae rather shallowly striated, n Schub = 9 or 10; metazonal setae relatively short (ca. 1/2 of metazonal length) and erect. Ozopores placed right in pro-metazonal suture in first several rings, gradually taking a more posterior position to ~ 1/2 of their diameter in caudalmost rings; sutures not sinuous in front of ozopores. Tarsus of mid-body legs 1.4-1.5 × as long as tibia and 3.6-3.9 × as long as apical claw.

Telson (Fig. 44B ): Epiproct very long, straight to slightly bent ventrad, ending with a pointed hyaline tip turned ventrad, considerably surpassing longest paraproctal setae in both sexes. Hypoproct in males trapezoidal, tridentate, teeth well-developed, robust, protruding behind rear contour of paraprocts; the same being broadly rounded, completely concealed below paraprocts in females; ventral surface with five submarginal setae. Paraprocts moderately densely setose (ca. 20 long setae each side), without distinct rows of shorter setae along caudal margins.

Male sexual characters: Mandibular stipites moderately expanded, protruding ventro-anteriad, forming a broadly rounded anterior corner. Leg pair 1 (Fig. 45A, B ) compact hooks turned somewhat against one another, bearing minute tarsal remnants (white arrow) in some specimens. Leg pair 2 and following pairs with crested adhesive pads ventrally on tibia and postfemur, these gradually reduced towards telson, completely disappearing in caudalmost legs; femora of legs 3-7 with an oval groove. Pleurotergum 7 ventrally forming large rounded lobes (Fig. 45C ) originating mostly from metazona, protruding ventromesad behind gonopods. Penis (Fig. 45D, E ) somewhat longer than broad, strongly compressed anterocaudally, with diverging apical lobes and well-developed, tapering, terminal lamellae.

Gonopods (Fig. 46 ): In situ protruding from gonopodal sinus with their apical parts, laterally not concealed by protrusions of pleurotergum 7. Promere (Fig. 46A ) as high as opisthomere, being conspicuously similar to that of O. kvavadzei sp. nov. and O. ponticus sp. nov. in overall shape, and particularly in having a short and strongly pronounced median ridge and a distomesal micro-squamous lobe; differing mostly by the broader apex. Opisthomere (Fig. 46B-E ) rather slender; basoposterior process a well-developed and massive lobe, deeply divided from CBO, ending in a small, pointed, apical outgrowth bent anteriad; anterior process shaped as a furrowed lamellar ridge, completely fused to CBO; mesomeroidal lobe strongly pronounced, positioned at base of opisthomere, without any expanded parts; solenomere markedly slender, somewhat bent posteriad; only a few scattered spiniform filaments near flagellum channel.

Female sexual characters: Leg pairs 1 and 2 somewhat thicker than following legs, leg pair 3 also slightly thicker and somewhat longer than neighbouring pairs. Vulva (Fig. 45F ) very similar to that in O. ponticus sp. nov., including the external shape of the bursa, the structure of the receptaculum seminis, and the very high operculum; differs by a larger opening and a smaller central tube in relation to both posterior tube and ampulla.

General distribution.

LECA.

Figures

Figure 44. Omobrachyiulus trochiloides sp. nov. A habitus of ♀ paratype from Baniskhevi Valley, Georgia (ZMUM) B telson of ♂ holotype, lateral view. Not to scale.

Figure 45. Omobrachyiulus trochiloides sp. nov., ♂ (A, B, D, E) and ♀ (F) paratypes from Baniskhevi Valley, Georgia (ZMUM), and ♂ paratype from near Nabeglavi, Georgia (NMNHS) (C) A leg pair 2, caudal view B distal part of left leg 1, caudal view C left flange of pleurotergum 7, ventro-lateral view D penis, caudal view E same, lateral view F left vulva, caudo-mesal view. Scale bars: 0.1 mm (A, C), 0.2 mm (D-F), not to scale (B). Abbreviations: ct central tube op operculum pa posterior ampulla pt posterior tube.

Figure 46. Omobrachyiulus trochiloides sp. nov., gonopods of ♂ paratypes from Baniskhevi Valley, Georgia (ZMUM) (A-D) and from near Nabeglavi, Georgia (NMNHS) (E) A left promere (flagellum broken off), caudal view B right opisthomere, mesal view C distal part of the same aspect D right opisthomere, lateral, somewhat caudal view E distal part of right opisthomere, lateral view. Scale bars: 0.2 mm (D), 0.1 mm (A, B, E), 0.05 mm (C). Abbreviations: ao apical outgrowth of basoposterior process, ap anterior process, bpp basoposterior process, dml distomesal lobe, f flagellum, fc flagellum channel, ml mesomeroidal lobe, mr median ridge, s solenomere.