Koiulus interruptus, Enghoff & Jensen & Mikhaljova, 2017

Enghoff, Henrik, Jensen, Laura Mark & Mikhaljova, Elena V., 2017, A new genus of mongoliulid millipedes from the Far East of Russia, with a list of species in the family (Diplopoda, Julida, Mongoliulidae), European Journal of Taxonomy 326, pp. 1-19 : 3-9

Koiulus interruptus gen. et sp. nov.

urn:lsid:zoobank.org:act:04617A80-8F8D-47E0-A237-F1A5030EBAA8

Figs 1–9

Etymology

The species is named after the interrupted series of ozopores.

Material examined

Holotype

RUSSIA: ♂, Khabarovskii Krai (southern), Sikhote-Alin (Central) range, upper course of river Ko, 47.074° N, 136.478° E, 700–800 m, fir-birch forest, 23–25 May 2015, wet leaf litter, A. Hansen, M. Justesen and A. Solodovnikov leg., sample RUS 15-7a ( ZMUC 00040235 ).

Paratypes

RUSSIA: 4 ♂♂ (incl. 2 used for SEM), 18 ♀♀ (incl. 1 used for SEM), 8 juv. ♂♂, 1 juv. unsex., same data as holotype ( ZMUC 00040238); 2 ♂♂, 2 ♀♀, 1 juv. ♂, same data as holotype ( ZMUM P 3534); 2 ♂♂, 3 ♀♀, same data as holotype, but 47.037° N, 136.396° E, 580 m, mixed forest, 22 May 2015, leaf litter and river bank and flood debris, samples RUS 15-6a and RUS 15-6b ( ZMUC 00040239, ZMUC 00040240); 2 ♂♂, 4 ♀♀, 2 juv. ♂♂, 2 juv. ♀♀, same data as holotype, but 47.0716° N, 136.4572° E, 750 m, firbirch forest, 26 May 2015, leaf litter, samples RUS 15-8a and RUS 15-8e ( ZMUC 00040241, ZMUC 00040242); 3 ♂♂, 2 ♀♀, same data as holotype, but 47.04° N, 136.37° E, 400–500 m, mixed forest along the road, sample RUS 15-9 ( ZMUC 00040243); 1 ♂ (6 trunk fragments + slightly broken head + leg pairs 1, 2 and 7, gnathochilarium and gonopods in Canada balsam), Khabarovskii Krai, ca 75 km SE of Khabarovsk, environs of Zolotoi village, mixed forest, 5 Oct. 1981, G.N. Ganin leg. ( FSCB).

Description

MEASUREMENTS. See Fig. 2 for a graphical representation of size parameters. Males: length (14) 19– 20 mm (all males from river Ko site 19–20 mm), diameter 0.94–1.01 mm, 38–44 podous rings + 2–5 apodous rings in front of telson (fewer apodous rings in larger males). Females: length up to 21 mm,

diameter up to 1.31 mm, up to 46 podous rings + at least one, usually 2–5 apodous rings in front of telson (fewer apodous rings in larger females).

COLOUR ( Fig. 1 ). Marbled brownish, darker dorsally, no pronounced colour pattern. Defense glands visible as dark spots on the body rings on which they occur (see below). Male from environs of Zolotoi village beige (probably faded by preservation). Eye patches black. Antennae brown.

EYE PATCHES. Subtriangular, composed of 30–45 ocelli. A pair of long frontal (epicranial) setae (broken in many specimens), at least some individuals with scattered additional long setae between antennal sockets and labrum. 2+2 supralabral setae, at least 5+5 labral setae.

ANTENNAE. Reaching body ring 3 when folded back. Antennomeres 5, 6 and 7 each with an external subapical group and corolla of sensory bacilli; sensory bacilli of antennomere 7 minute. Antennomere 3 longer than the others: 3>2≈4≈5>6>>7>1.

MANDIBLES ( Fig. 3 A–C). External tooth (odontomere of Hoffman & Howell 1995), with three cusps decreasing in size from posterior to anterior. Internal tooth (dentate lamella of Hoffman & Howell 1983, sectile edge of psectromere of Hoffman & Howell 1996), with ca 5 cusps decreasing in size from posterior to anterior. Eight rows of simple pectinate teeth. Molar plate without grooves, with a row of hand-like processes, each with 3–5 bent ‘fingers’, along anterior margin.

GNATHOCHILARIUM ( Fig. 3 D–E). Three apical setae on each stipes and four or five setae in a longitudinal row on each lamella lingualis; promentum (modified in male, see below) completely separating lamellae linguales.

COLLUM ( Fig. 4B ). Smooth, with one or two striae along lower margin.

BODY RINGS ( Figs 1 , 4 A–D). Slightly vaulted, prozonites smooth, metazonites with longitudinal striae in ventral half. A row of short setae on posterior margin, length of setae ca 0.1 × body diameter. Ozopores present from ring 6 onward, but missing from rings 7, 11, 14 or 15, one of rings 17–20 and several single rings further backward ( Fig. 4C ).

TELSON ( Figs 1 , 4A ). Preanal ring with a short dorsal process and setae along posterior margin. Anal valves each with two setae. Subanal scale with two setae.

LEGS ( Figs 1 , 4 A–C). Moderately long and slender. Claws long, weakly curved, without modifications.

Male sexual characters

MANDIBLES ( Fig. 4B ). Stipes with a small, protruding, ventro-posterior lobe.

GNATHOCHILARIUM ( Fig. 3 D–E). Promentum swollen, transversely microstriate, anteriorly produced in triangular tip overreaching lamellae linguales.

FIRST PAIR OF LEGS ( Figs 4 A–B, 5A–C). Strongly enlarged, consisting of an unpaired coxosternum and five-segmented telopodites. Interpretation of basal sclerite as a coxosternum supported by narrow ‘trochanters’ (not visible on Fig. 5 ) situated between unpaired sclerite and each of the telopodites. Third telopodomere longer than the others: 3>4>1> 2>5. Telopodomore 1 (prefemur?) massive, ca as broad as long, with an area densely covered in short bristles on anterior side (obscured by a secretion-like substance on imaged specimen). Telopodomere 2 (femur?) much broader than long, with a hump on anterior surface, i.e., in inner curvature of telopodite. Telopodomere 3 (postfemur, or postfemur + tibia?) much longer than any of the others, its basal ca 40% flattened, much more slender than distal ca 60%. Telopodomere 4 (tibia, tarsus, or tibia+tarsus?) flattened, of uniform width throughout. Telopodomere 5 (strongly reduced tarsus or claw?) very small, hemisphaerical. Telopodomeres 1–4 with scattered setae, 5 entirely smooth.

SECOND PAIR OF LEGS ( Fig. 5 D–F). Strongly reduced, consisting of an unpaired (coxo?)sternum and threesegmented telopodites. Telopodomere 1 cylindrical, gently curved, ca 3 times as long as broad, with scaly microsculpture on posterior surface and a long disto-mesal seta on anterior surface. Telopodomere 2 barrel-shaped, slightly longer than broad, with a long disto-mesal seta on anterior surface and several shorter, scattered setae. Telopodomere 3 contrastingly black, tapering to narrow tip, here with a bunch of ca 7–8 stout setae with irregularly multi-spiked tips ( Fig. 5F ); several normal setae scattered over telopodomere surface.

PENIS ( Fig. 5 D–E). Unpaired, cylindrical, longer than second legs, gradually narrowing towards end or with a slender, parallel-sided tip.

SEVENTH PAIR OF LEGS ( Figs 5 G–I, 6). Strongly reduced, each leg consisting of three-four podomeres of uncertain homology. Podomere 1 almost twice as long as podomere 2; podomere 1, sometimes also podomeres 2 and 3, with scaly microsculpture on mesal surface and a long (disto-)mesal seta, podomere 2 further with a few short setae. Podomere 3 contrastingly black, pear-shaped or conical, smooth or with a few short setae, sometimes surmounted by a tiny podomere 4 carrying 5 strong setae laterally and a claw apically ( Fig. 6 ).

SEVENTH PLEUROTERGITE ( Fig. 4 B–C). With triangular-rounded ventral lobes (protecting gonopods).

ANTERIOR GONOPODS ( Fig. 7 ). Coxal processes (CX) separate, long and slender, slightly curved posteriad, laterally excavated for accommodation of telopodites, tips rounded. Flagella (FL) strongly reduced, short, finger-like, projecting perpendicularly from coxal process, with strong scaly microsculpture. Telopodite (TLP) almost as long as coxal process, apically with large mesal lobe; tip of lobe with scaly microsculpture and a group of ca 6 short setae. Remaining surface of telopodite smooth, except for some tiny (~ 10 µm) sub-circular, densely porose structures (PS, Fig. 7 C–D).

POSTERIOR GONOPODS ( Fig. 8 ). Each posterior gonopod divided from the basis into two equally long branches. Anterior branch (AB) slender, almost parallel-sided, mesally excavated, apical ⅓ with dense cover of retrorse mico-spicules; tip slender, curved up in densely microspiculate spiral. Posterior branch (PB) broad at base, tapering regularly towards tip and hence with a triangular outline; anterior surface excavated for accommodation of anterior branch; an anterior-lateral row of ca 15 short setae; mesal margin distally with subtriangular, anteriad lobes.

Female sexual characters

VULVA ( Fig. 9 ). Placed vertically in short vulval sacs behind unmodified second leg-pair, very slender, oblong pyriform. Operculum (OP) slightly longer than bursa, with two parallel rows of short setae on anterior surface and several strong setae on distal half; tip subtriangular. Bursa (BU) consisting of a single sclerite, but with longitudinal sutures in basal ¾ of mesal and lateral sides; four longitudinal rows of setae, one on each side of the two longitudinal sutures. Posterior surface apically divided into two rounded lobes.

A tiny (~ 15 µm) structure of unknown identity was observed next to one of the apical bursal setae ( Fig. 9D (arrow)–E). It is sausage-shaped, has an apical pore and is apparent attached by its basal end to the surface of the bursa as well as laterally attached to the neighbouring seta.

Figures

Fig. 1. Koiulus interruptus gen. et sp. nov., paratype, juvenile male from upper course of river Ko. Notice interrupted series of defense glands. Scale bar: 1 mm.

Fig. 2. Koiulus interruptus gen. et sp. nov. Body size as expressed by number of podous body rings and midbody diameter.

Fig. 3. Koiulus interruptus gen. et sp. nov., paratype, ♂, from the upper course of the river Ko. A. Left mandible. B. Molar plate of left mandible. C. Handlike processes on anterior margin of molar plate. D. Gnathochilarium. E. Lamellae linguales and modified promentum of gnathochilarium. Scale bars: A, E = 0.02 mm; B = 0.01 mm; C = 0.001 mm; D = 0.1 mm.

Fig. 4. Koiulus interruptus gen. et sp. nov., paratype, ♂, from the upper course of the river Ko. A. Entire body, 39 podous + 3 apodous body rings + telson. B. Anterior end. C. Body rings (5)6–12(13); note absence of ozopores on rings 7 and 11 (arrows). D. Leg-pair 7 and gonopods in situ. 7 = seventh body ring with ventral lobes. Scale bars: A =1 mm; B–C = 0.2 mm; D = 0.1 mm.

Fig. 5. Koiulus interruptus gen. et sp. nov., paratype, ♂, from the upper course of the river Ko. A–C. First pair of legs. A. Anterior view. B. Sublateral view. C. Tips. – D–F. Second pair of legs, and penis. D. Anterior view. E. Lateral view. F. Modified setae on tip of leg. – G–I. Seventh pair of legs. G. Ventral view. H. Posterior-ventral view. I. Tip of one telopodite. P = penis. Scale bars: A, G = 0.1 mm; B, D, H = 0.05 mm; C, E, I = 0.02 mm; F = 0.005 mm.

Fig. 6. Koiulus interruptus gen. et sp. nov., paratype, ♂, from the environs of the village of Zolotoi, seventh pair of legs. A. Ventral view. B. Tip of the telopodite. Scale bars: A = 0.5 mm; B = 0.1 mm.

Fig. 7. Koiulus interruptus gen. et sp. nov., paratype, ♂, from the upper course of the river Ko, anterior gonopods. A. Posterior view. B. Modified flagellum. C. Tip of left telopodite. D. Porose structure from telopodite. Abbreviations: CX = coxal process; FL = flagellum; PS = porose structure; TLP = telopodite. Scale bars: A = 0.1 mm; B–C = 0.01 mm; D = 0.001 mm.

Fig. 8. Koiulus interruptus gen. et sp. nov., paratype, ♂, from the upper course of the river Ko, posterior gonopods. A. Anterior view. B. Posterior-lateral view. C. Posterior-apical view. Abbreviations: AB = anterior branch; PB = posterior branch. Scale bars = 0.02 mm.

Fig. 9. Koiulus interruptus gen. et sp. nov., paratype, ♀, from upper course of river Ko, right vulva. A. Lateral view. B. Anterior view. C. Mesal view. D. Tip, posterior view; arrow points to unknown structure. E. Unknown structure from opercular seta. Abbreviations: BU = bursa; OP = operculum. Scale bars: A–C = 0.1 mm; D = 0.01 mm; E = 0.001 mm.