Micropachyiulus caucasicus Vagalinski & Evsyukov & Chumachenko & Zabiyaka 2023, sp. nov.
Creators: name: Vagalinski, Boyan
name: Evsyukov, Aleksandr P.
name: Chumachenko, Yuri A.
name: Zabiyaka, Igor Y.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Julida
Julidae
Micropachyiulus
Micropachyiulus caucasicus

description: Micropachyiulus caucasicus sp. nov.
Figs 1D, E, 5–7
Material examined (ZMUM). Holotype: ♂, Russia, Krasnodar Province, Khosta, Caucasian Nature Reserve, Taxus & Buxus grove, soil (0–15 cm), 25.III.2016, Y. Chumachenko leg.
Paratypes: 5 ♂♂ (two unbroken, three in 2 or more pieces; head, leg-pair 1 and gonopods of one prepared for SEM; head, gonopods and most of body of another prepared for SEM), 9 ♀♀ (7 unbroken, one in 3 pieces, another in 2 pieces, both with dissected vulvae), same collecting data as for holotype.
Diagnosis. A species of Micropachyiulus with ommatidia. Most similar to Micropachyiulus filiformis sp. nov., both being characterized by a very long and thin solenomere of the opisthomere, without apical bulge or projection, a minute, spike-like outgrowth of the mesomeral process, and an opisthomeral posterior lamella expanding in a mesal ridge partly concealing the distal section of the sperm channel.
Differs from M. filiformis sp. nov. by a bulging vs. flat anterior surface of the opisthomere, by the posterior lamella being smooth vs. overgrown with setiform filaments, by the promere gradually narrowing towards apex, vs. abruptly constricting in the middle, by the longer and more roughly serrated distal ridge of the latter, as well as by the shape of male legs 1: without tarsal remnants vs. the latter present as micropapillate bulges, and with slender vs. broad, flattened tibial outgrowths.
Also resembles M. paucioculatus by the very long solenomere of the opisthomere, but differs clearly from it by the solenomere lacking an apical bulge or projection and by the minute, spike-like (vs. well-developed, slender) outgrowth of the mesomeral process.
Etymology. After its provenance from the Caucasus region. Adjective.
Description. Measurements: Holotype with BRF 40 + 1 + T, L = 7 mm, H = 0.55 mm; paratype ♂♂ with BRF 35–39 + 1–2 + T, L = 6–7 mm, H = 0.47–0.5 mm; paratype ♀♀ with BRF 33–42 + 1–3 + T, L = 5–9 mm, H = 0.5–0.52 mm.
Colouration (after several years in ethanol) (Fig. 1D, E): mostly yellowish-beige, prozonae dorso-laterally light brown.
Head (Fig. 5B): With 3–5 pigmented ommatidia arranged in one or two rows on each side. Vertigial, supralabral and labral setae: 2, 4 and 13–14, respectively. Antennae (Fig. 5A) 1.5 times as long as head in males and 1.4 times in females; antennomere 5 ≥ 2> 4> 3> 6; 5 ca 1.5 times as long as broad and ca 1.6 times as broad as 2; size and distribution of sensilla as in M. paucioculatus. Mandibular stipites in males not expanded. Labrum tridentate. Gnathochilarium with 3 long distal setae on each stipes, proximal parts completely non-setose, stipital palps as in M. paucioculatus; promentum rather small, separating lamellae linguales in ca their proximal 1/3, the latter each bearing three more or less equally spaced setae in a row.
Trunk and legs: Collum completely smooth. Body rings (Fig. 5C) insignificantly vaulted. Prozonae completely smooth, except for their anteriormost sections (normally covered by the preceding ring’s metazona) having finely reticulated texture. Metazonae shallowly and rather sparsely striated, striation becoming deeper and denser ventrally, dorsally and laterally not crossing entire length of metazona; metazonal setae rather short, mostly fallen off. Ozopores (oz in Fig. 5C) set tightly behind pro-metazonal suture in more anterior rings, and somewhat further back (up to 2 x their diameter) in more posterior rings. Walking legs relatively short: ML ca 0.7 times as long as H in males and 0.6 times in females. Tarsus of ML ca 1.5 times as long as tibia and ca 2.3 times as long as apical claw. Accessory claws absent from all legs in both sexes.
Telson: Pre-anal ring sparsely but evenly covered with long setae. Epiproct relatively long (nearly reaching level of tip of longest paraproctal setae), straight to slightly bent ventrad, wedge-like, ending with a fine, sharply pointed hyaline tip (often broken off). Hypoproct of same shape as in M. paucioculatus; ventrally with two submarginal setae. Pilosity on paraprocts of moderate density, without distinct row of shorter setae along posterior margins.
Male sexual characters: Legs 1 (Fig. 5D) 3-segmented hooks oriented (almost) completely mesad, and (sometimes) slightly anteriad; tibial outgrowth rather slender, tarsal remnant indistinct or absent; the distal podomere baso-mesally with a verrucose hump (h). Leg-pair 2 (Fig. 7A) considerably ticker and slightly longer than following legs. Ventral adhesive pads altogether absent. Flanges of pleurotergum 7 (Fig. 7C) ventrally forming rather narrow shovel-like lobes originating at the border zone between pro- and metazona, directed ventro-mesad.
Gonopods (Figs 6, 7D) in situ mostly concealed in gonopodal sinus. Promere (Fig. 6B and P in Figs 6A, D, 7D) relatively slender, slightly overreaching opisthomere, gently sigmoid in anterior or posterior views, gradually narrowing towards a rounded apex directed somewhat mesad; mesal ridge (mr) well-developed, roughly pyramidal, with a pointed tip, mesally bearing several very short setiform filaments; lateral ridge (lr) short and rather weakly pronounced; distal ridge (dr) large and strongly pronounced, marginally densely denticulate; median groove indistinct. Opisthomere (Fig. 6C, E, and O in Figs 6A, D, 7D) stouter than in M. paucioculatus, very slightly sigmoid in lateral and mesal views, antero-basally somewhat bulging; mesomeral process (m) weakly pronounced, lamellar, completely undivided from the opisthomere, apically forming a minute spike-like outgrowth (mp) directed anteriad or baso-anteriad; posterior lamella (l) well-developed, expanding in a large mesal crest concealing distal section of sperm channel (sc); setiform filaments absent; solenomere (s) long and very fine, thread-like/flagelliform.
Female sexual characters: Leg-pairs 1 (significantly) and 2 (slightly) ticker and somewhat shorter than following pairs. Vulva (Fig. 7E) stout, somewhat compressed on sides, roughly conical in side view; median field (mf) deeply concave, elongate, extending proximally to almost mid-height of bursa; operculum (op) higher than bursa, broad, with a concave apical margin, apical corners extended into hyaline protrusions, mesal one larger than lateral one; two smaller and tapering protrusions present apically on bursa; each bursal valve bearing two distal setae, operculum non-setose. RS composed of a narrow, somewhat folded central tube (ct) ending in an ovoid central ampulla (ca), and a posterior tube (pt) of similar length and gauge as the central tube, ending in a piriform posterior ampulla (pa) of similar size as the central one.
Distribution (Fig. 14, purple circle). Russia: Krasnodar Province: Caucasian Nature Reserve (type locality).
description: Published as part of Vagalinski, Boyan, Evsyukov, Aleksandr P., Chumachenko, Yuri A. & Zabiyaka, Igor Y., 2023, A review of the genus Micropachyiulus Verhoeff, 1899 and description of the related Armeniopachyiulus gen. nov. (Diplopoda: Julida: Julidae: Pachyiulini), pp. 221-246 in Zootaxa 5239 (2) on pages 231-235, DOI: 10.11646/zootaxa.5239.2.3, http://zenodo.org/record/7624205