Micropachyiulus paucioculatus ( Verhoeff, 1899 )

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), Zootaxa 5239 (2), pp. 221-246 : 228-231

Micropachyiulus paucioculatus ( Verhoeff, 1899)

Figs 1A , 3 , 4

Pachyiulus (Micropachyiulus) paucioculatus Verhoeff, 1899: 184–185 , figs 1–4

Pachyiulus (Micropachyiulus) paucioculatus: Verhoeff (1900: 211)

Pachyiulus paucioculatus: Verhoeff (1900: 220)

Micropachyiulus paucioculatus: Verhoeff (1907: 460) ; Attems (1926a: 259); Kime & Enghoff (2017: 133) ; Giurginca (2021: 200–201, fig. 156)

Micropachyiulus pauciocalatus (sic!): Verhoeff (1907: 461)

Micropachyiulus pauciocellatus (sic!): Kime & Enghoff (2017: 270)

Material examined. Syntypes ( MNB): Pachyiulus paucioculatus Verhoeff, Valea Corbului , slide preparations 1138–1140: antennae, legs, gonopods, mouthparts, flanges of male pleurotergum 7 . Other material: 3 ♂♂, 3 (supposedly) adult ♀♀, 1 frontal part of an (supposedly) adult ♀, 1 (supposedly) subadult ♀ ( IBER), Romania, Oltenia , Motru Sec, Cloşani, slope at roadside, 45.0809°N, 22.8014°E, 400 m a.s.l., mostly Fagus , in and under leaf litter in a mixture of soil and fine gravel, 30.X.2021, H. Reip, K. Voigtländer, D. Antić, D. Stojanović, and B. Vagalinski leg.; 2 ♂♂, 2 (supposedly) adult ♀♀ ( NHMW MY 10327 ), same collecting data .

Diagnosis. A species of Micropachyiulus with ommatidia, being very similar to Micropachyiulus corylorum , Micropachyiulus ocellatus comb. nov. and Micropachyiulus pygmaeus in terms of gonopod conformation, and especially in the shape of the solenomere which ends up with a minute, transversely oriented apical projection. Differs from all these species by a much longer solenomere (considerably overreaching the apical part of the posterior lamella, vs. being subequal to it) and an apically smooth rather than serrate or fimbriate posterior lamella. Differs further from M. corylorum by the absence of an opisthomeral rod-like process just behind the solenomere; from M. ocellatus comb. nov. by a more slender apical outgrowth of the mesomeral process, running mostly parallel to the main axis of the opisthomere rather than deviating anteriad; and from M. pygmaeus by a long and pointed (vs. very short and blunt) epiproct and a more slender promere.

Also resembles M. caucasicus sp. nov. and M. filiformis sp. nov. by the very long solenomere, but differs clearly from both of them by the solenomere lacking an apical bulge or projection and by the well-developed, slender (vs. minute, spike-like) outgrowth of the mesomeral process.

Redescription. Measurements: ♂♂ with BRF 31–39 + 3 + T, L = 6–8.2 mm, H = 0.41–0.50 mm; ♀♀ with BRF 34–43 + 2–3 + T, L = 8.3–9.7 mm, H = 0.53–0.69 mm .

Colouration ( Fig. 1A ): light beige to brownish, living specimens with purple tinges, gut and the reddish repugnatorial glands partly visible by transparency.

Head ( Fig. 3A ): With 1–4 pigmented ommatidia arranged in one or two rows on each side. Vertigial, supralabral and labral setae: 2, 4 and 13–14, respectively. Antennae 1.4–1.55 times as long as head in males and 1.2–1.3 times in females; antennomere 5 ≥ 2 ≥ 3 = 4> 6; 5 1.5–1.6 times as long as broad and ca 1.7 times as broad as 2; 5 and 6 with a row of several sensilla basiconica dorsally and laterally at distal margins, those on 5 of slightly larger than the four apical sensilla, those on 6 considerably smaller. Mandibular stipites in males not expanded. Labrum tridentate. Gnathochilarium with 3 long distal setae and a short medial one on each stipes, stipital palps relatively small, each bearing several minute apical sensilla; promentum medium-sized, separating lamellae linguales in ca their proximal 2/5, the latter each bearing three more or less equally spaced setae in a row.

Trunk and legs: Collum completely smooth. Body rings slightly to moderately vaulted. Prozonae mostly smooth, with some very short and shallow striae next to suture. Metazonae with shallow and rather sparse parallel striae, mostly crossing entire length of metazona; metazonal margins with a rather dense whorl of erect to slightly slanting setae, those on anterior and mid-body rings ca 0.25 times as long as H in males, ca 0.18 in females, those on posterior rings ca 0.33 and 0.23 times in males and females, respectively. Ozopores set tightly behind pro-metazonal suture in most rings, and slightly further back (up to 1.5x their diameter) in posterior-most rings. Walking legs relatively short: ML 0.65–0.7 times as long as H in males and 0.55–0.65 times in females. Tarsus of ML ca 1.8 times as long as tibia and ca 2.6 times as long as apical claw. Male legs 2 ( Fig. 4B ) with a short accessory claw, next pairs without; a similarly developed accessory claw in female legs 1 and 2, next pairs without.

Telson: Pre-anal ring evenly and rather densely covered with long setae. Epiproct rather long (reaching level of tip of longest paraproctal setae), proximally straight, wedge-like, distally extending in a very slender, pointed, hyaline tip directed more or less ventrad. Hypoproct small, broadly rounded, tightly adhering under paraprocts in both sexes; ventrally with a pair of submarginal setae. Paraprocts moderately densely setose, without distinct row of shorter setae along posterior margins.

Male sexual characters: Leg-pair 1 ( Figs 3B , 4A ) 3-segmented hooks oriented (almost) completely mesad, and (sometimes) very slightly anteriad; tibial outgrowth rather slender and tapering, tarsal remnant usually present as a minute spike; the distal podomere baso-mesally with a verrucose hump (h). Leg-pair 2 ( Fig. 4B ) visibly longer and ticker than following legs. Ventral adhesive pads altogether absent. Flanges of pleurotergum 7 ( Fig. 4C ) ventrally forming broad, rounded lobes originating at the border zone between pro- and metazona, directed mostly mesad.

Gonopods ( Figs 3C–E , 4D ) in situ mostly concealed in gonopodal sinus, only tips of promeres visible on the outside, pro- and opisthomere (with tip of solenomere) subequal in height. Promere ( Fig. 3C and P in Fig. 4D ) slender, sigmoid in mesal and lateral views, gradually narrowing towards a broadly rounded or flattened apex; posterior surface with a short and weakly pronounced mesal ridge (mr), a similarly developed lateral ridge (lr), and a rather small, oblique, distal ridge (dr) bearing about a dozen small denticles, with some being present also basally to the ridge; a very deep and narrow median groove (mg) between mesal and lateral ridges. Opisthomere ( Fig. 3D, E and O in Fig. 4D ) relatively slender, gently sigmoid in mesal and lateral views (distally bent anteriad); mesomeral process (m) weakly pronounced, lamellar, ending with a small blunt outgrowth (mp) directed distad; posterior lamella (l) well-developed, expanding into a mesal crest apically forming a minute tapering outgrowth; mesal surface with numerous setiform filaments (sf) between posterior lamella and sperm channel (sc); solenomere (s) in the shape of a long and thin rod with a small apical projection (sp) set transversely to main axis of solenomere.

Female sexual characters: Leg-pairs 1 and 2 slightly ticker and shorter than following pairs. Vulva ( Fig. 4E ) subconical, stout, somewhat compressed on sides; median cleft positioned sub-apically, surrounded by a small and shallow median field; operculum (op) significantly higher than bursa, apically strongly concave, ending up with a large, rounded hyaline protrusion on each side; two smaller and tapering protrusions present apically on bursa; each bursal valve bearing two setae, operculum non-setose. RS composed of a rather long digitiform central tube (ct), only slightly widening towards bottom rather than forming a distinct ampulla; and a long and narrow, folded, posterior tube (pt) ending in an ovoid posterior ampulla (pa).

Distribution ( Fig. 14 , green circles). Romania: South Carpathians: Mehedinți Mts: CloȘani karst area ( Giurginca 2021, present study); Şureanu Mts: near Bolii Cave, Corbului Valley near Pui (original localities).

Remark. This species is probably a troglophile, as it shows preference for limestone areas where it has been found in both caves and external habitats ( Kime & Enghoff 2017).

Figures

FIGURE 1. Micropachyiulus spp., habitus. A. Micropachyiulus paucioculatus (Verhoeff, 1899), living female from Cloşani, Romania. B. and C. Micropachyiulus filiformis sp. nov., living ♂ (NMNHS) and ♀ paratypes, respectively. D. and E. Micropachyiulus caucasicus sp. nov., ♂ and ♀ paratypes (ZMUM), respectively. Scale bars: 0.5 mm. A–C taken not to scale. Photo credit: A. H. Reip, B. and C. D. Antić.

FIGURE 3. Micropachyiulus paucioculatus (Verhoeff, 1899), ♂ from Cloşani, Romania (IBER). A. Head, ventral view. B. Right leg 1, anterior view. C. Right promere, posterior view. D. Left opisthomere, mesal view. E. Right opisthomere, lateral view. Abbreviations: dr: distal ridge, h: verrucose hump, l: posterior lamella, lr: lateral ridge, m: mesomeral process, mg: median groove, mp: apical outgrowth of mesomeral process; mr: mesal ridge, s: solenomere, sc: sperm channel, sf: setiform filaments, sp: apical projection of solenomere. Scale bars: 0.1 mm (A, C–E), 0.05 mm (B).

FIGURE 4. Micropachyiulus paucioculatus (Verhoeff, 1899), ♂ (A–D) and ♀ (E) from Cloşani, Romania (IBER). A. Legpair 1, anterior view. B. Left leg 2, anterior view. C. Right flange of pleurotergum 7, ventro-lateral view. D. Right gonopods, mesal view. E. Right vulva, postero-lateral view. Abbreviations: ct: central tube, h: verrucose hump, l: posterior lamella, m: mesomeral process, mp: apical outgrowth of mesomeral process, O: opisthomere, op: operculum, P: promere, pa: posterior ampulla, pt: posterior tube, s: solenomere, sf: setiform filaments, sp: apical projection of solenomere. Scale bars: 0.1 mm.

FIGURE 14. Distribution of the genera Micropachyiulus Verhoeff, 1899 and Armeniopachyiulus gen. nov.