Typhloiulus bulgaricus, Vagalinski, Boyan, Stoev, Pavel & Enghoff, Henrik, 2015

Vagalinski, Boyan, Stoev, Pavel & Enghoff, Henrik, 2015, A review of the millipede genus Typhloiulus Latzel, 1884 (Diplopoda: Julida: Julidae), with a description of three new species from Bulgaria and Greece, Zootaxa 3999 (3), pp. 334-362 : 346-349

Typhloiulus bulgaricus sp. n.

Figs 8–19

Material. Holotype ♂ broken into 2 pieces and body ring 7, gonopods mounted on slide ( NMNHS), Bulgaria, Pleven Distr., v. Gortalovo, cave Aladzhanskata peshtera, 2.VII.1985, B. Garev leg.

Paratypes: 1 ♂ (in two pieces, gonopods mounted for SEM, 3rd, mid-body and posterior body leg, and penis mounted on slide), 3 ♀ (broken into 2 or more pieces; one left vulva mounted for SEM, vulva and mouthparts of another specimen dissected and placed in a microvial), 1 juv. (intact), same locality and collecting data as of the holotype ( NMNHS).

Diagnosis. Differs from congeners by a combination of a laciniate velum and the absence of an intermediate lamella of the opisthomere; promere spoon-shaped, apically not bent; preanal process well-developed, pointed, directed slightly downward; mouthparts unmodified.

Etymology. Self-evident. Adjective.

Description. Holotype with 37+2+T body rings, length 15 mm, height 0.8 mm. Paratype ♂ with 41+1+T body rings, length 18 mm, height 0.9 mm. Paratype females with 36+2+T body rings, length 13 mm, height 0.8 mm; 35+2+T body rings, length 14 mm, height 0.8 mm; 38+2+T body rings, length 18 mm, height 0.9 mm.

Colouration: uniformly pale yellowish-beige, probably further decolourated due to alcohol conservation.

External structures: 4 supralabral and 14 labral setae. Labrum tridentate. Antennomeres 2, 3, 4 and 5 more or less equally long, considerably longer than 6th; antennomere 5 with a group of long sensilla basiconica (of similar size as the 4 sensilla on the antennal apex) laterally; similar, but slightly smaller sensilla present on antennomere 6. Gnathochilarium of normal julid appearance, with 3 apical setae on each stipes and with 4–5 setae in a row on each lingual plate; promentum relatively large, 2–2.3 times longer than broad, 0.59–0.63 times as long as lingual plates. Collum smooth, with just 3–4 very shallow longitudinal grooves near postero-lateral corner. Prozonae smooth. Metazonae perceivably, but rather scatteredly striated, with 4–5 striae in a square with sides equal to metazonal length just below ozopore level; a dense whorl of erect setae at metazonal hind margin; longer and shorter setae alternating, the longer ones ca ½ of metazonal length. Ozopores placed behind pro-metazonal suture at ca 1/4–1/3 of metazonal length. Telson ( Fig. 8 ): preanal process moderately long, dorso-ventrally flattened, pointed, somewhat turned downwards, equal to or slightly surpassed by longest anal setae; subanal scale subtriangular, with a rounded tip, barely protruding behind rear contour of anal valves; anal valves sparsely pilose, with two distinct rows of shorter (ca ½ of lateral) setae along caudal margins. Male pleurotergum 7 ( Fig. 9 ) with rounded protrusions, directed ventro-posteriad. Male legs: pair 1 converging, slightly turned upward hooks, without tarsal remnants; pair 3 ( Fig. 11 ) with a small, but pronounced adhesive pad (a) on tibia; mid-body legs ( Fig. 12 ) with a similar tibial pad (a) and with oval pits (p) on femur and postfemur; end-body legs ( Fig. 13 ) with a minute tarsal pad (a), without pits on femur and postfemur; tarsus of mid-body leg 2.4–2.5 times longer than tibia and 2.7–2.8 times longer than apical claw.

Penis ( Fig. 10 ): elongated, broadest at base, gradually narrowing up to its middle, then again slightly widening; apical lobes (al) short, stout, diverging, ending up with oblong, more or less parallel, terminal lamellae (tl).

Gonopods ( Figs 14–18 ): Rather elongated, in situ protruding with their distal parts from gonopodal sinus, opisthomere somewhat longer than pro- and mesomere, promere slightly exceeding mesomere. Promere ( Fig. 16 and P on Figs 14 & 15 ) more or less spoon- or shovel-shaped: gradually broadening towards a gently convex apical margin; distal part bent neither towards nor against mesomere, its caudal face densely tuberculate; parabasal internal lobe (il) oblong, with a flattened tip, with 3 apical setae; parabasal external lobe (el) quite large, leaf-like, exceeding height of internal lobe. Flagellum (f) thin, its apical part protruding above solenomere in intact gonopods. Mesomere (M on Figs 14 & 15 ) very slender, mostly straight, with a deeply and narrowly concave caudal face; apical part broadened, bent anteriad, with a smooth surface. Opisthomere ( Figs 14, 15, 17 & 18 ) slender, without processes except for a laciniate velum (v); intermediate lamella absent; basal spine (sp) short and thin, mostly straight; solenomere (s) simple, with two minute apical processes.

Vulva: ( Fig. 19 ): Somewhat compressed antero-caudally, slightly asymmetric: lateral valve higher and broader than mesal one. Opening (o) narrow and cleft-like, placed right in the center of bursa. 3 setae in a vertical row on each valve. Operculum (op) considerably exceeding bursa, with a broad, flat, apical margin. Receptaculum seminis consisting of a short, moderately thick, slightly bent central tube (ct) ending with an oblong central ampulla (ca), and a long, thin posterior tube (pt) forming several twists on its way to an egg-shaped posterior ampulla (pa).

Remarks. T. bulgaricus sp. n. shows a combination of unique gonopodal and somatic characters that none of the other congeners possesses. It resembles T. edentulus , from southwestern Bosnia and Herzegovina ( Attems, 1951), by having an identical branched velum and similar gonopod proportions. Strasser (1962) placed the latter species in the monotypic subgenus Attemsotyphlus Strasser, 1962 , which is outstanding by having an edentate labrum and modified mandibles, and by lacking a preanal process. None of these characters is present in T. bulgaricus sp. n., although the reduction of mouthparts is found in many unrelated julidans and thus of doubtful systematic value ( Enghoff, 1985), and is thought to be a trait that developed as a result of adaptation to a semiaquatic way of living.

Figures

FIGURES 8 – 13. Typhloiulus bulgaricus sp. n. holotype (9) and paratype male (8, 10 & 11 – 13) (NMNHS): (8) telson, lateral view; (9) left pleurotergal protrusion, latero-ventral view; (10) penis; (11) leg 3; (12) mid-body leg; (13) end-body leg. Abbreviations: a: adhesive pad, al: apical lobe, p: pit, tl: terminal lamella. Scale bars: 0.2 mm.

FIGURES 14 – 19. Typhloiulus bulgaricus sp. n. holotype (15 & 16), paratype male (14, 17 & 18) and paratype female (19) (NMNHS): (14) gonopod block, right half in mesal view; (15) left gonopods, lateral view; (16) left promere, caudal view; (17) right opisthomere, top-mesal view; (18) velum, top view; (19) left vulva, caudal view. Abbreviations: bs: basal spine, ca: central ampulla, ct: central tube, el: external lobe, f: flagellum, fc: flagellum channel, il: internal lobe, l: intermediate lamella, o: opening, op: operculum, M: mesomere, P: promere, pa: posterior ampulla, pt: posterior tube, s: solenomere, sf: seti-form filaments, v: velum. Scale bars: figs 15 & 16: 0.2 mm, fig. 19: 0.1 mm.