Typhloiulus orpheus, 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 : 349-352

Typhloiulus orpheus sp. n.

Figs 20–29

Typhloiulus n. sp.: Enghoff et al. 2013: p. 15, 21

Material. Holotype ♂ broken into 3 pieces, leg-pair 2 & penis dissected ( NMNHS); Bulgaria, Western Rhodopi Mts., v. Trigrad, in close proximity to cave Dyavolskoto garlo, limestone scree with sparse European spruce trees, some 15–20 cm below the surface, in gravel with some rootless, 27.V.2014, BV leg.

Paratypes ( NMNHS): 1 ♂ broken into 2 pieces; head + first 7 segments lost in the course of examination; gonopods, mid-body & end-body leg slide-mounted, same locality and collector as of the holotype, 15.VIII.2011; 2 ♀, 1 intact, 1 broken into 2 pieces, same locality and collector as of the holotype, 30.VII.2013; 4 ♀ (3 intact specimens, 1 broken into 2 parts, with dissected vulvae), 1 juv. (broken into 2 parts), same locality and collecting data as of the holotype.

Diagnosis. Resembles its most similar congener— T. kotelensis —especially by the presence of bumps at the caudal margin of the anal valves, a character seen in no other species of Typhloiulus ; differs from it by its smaller size, much paler colouration, relatively longer preanal process, and by gonopod details, viz., promere more or less parallel-sided with an almost straight apical margin, rather than gradually narrowing towards a broadly rounded apex; opisthomere straight, rather than bent anteriad in its distal part, with a less strongly developed intermediate lamella and a relatively smaller (compared to the solenomere) velum.

Etymology. After Orpheus , a mythical hero, musician, poet, and prophet in ancient Greek religion. The species was found in close proximity to the cave ‘Devil’s throat’ (Dyavolskoto garlo) which, according to a local belief, is the gate to the underworld. According to local believes, Orpheus should have passed through the cave in his travel to retrieve his wife Eurydice from the Kingdom of Hades. Noun in apposition.

Description. Holotype with 42+3+T body rings, l = 12 mm, h = 0.85 mm; paratype ♂ with 58+1+T body rings, h = 1.2 mm; paratype females (49–56)+(1–3)+T body rings, l = 14–19 mm, h = 0.95–1.2 mm.

Colouration: white to light yellowish, head and first several rings somewhat lighter than remaining body; gut partly visible through a semi-transparent tegument.

External structures: 4 supralabral and 18 labral setae. Labrum tridentate. Antennomeres 2, 3, 4 and 5 more or less equally long, ca 1.5 times longer than 6th; antennomere 5 with a group of long sensilla basiconica (longer than the 4 sensilla on the antennal apex) laterally; similar, but much smaller sensilla present on antennomere 6. Male mandibular stipites not enlarged. Gnathochilarium of normal julid appearance, with 3 apical setae on each stipes, and with 4 setae in a row on each lingual plate; promentum relatively small, ca 0.35 times as long as lingual plates, length to width ratio: 1.66. Collum smooth with 4–5 shallow striae at postero-lateral corner. Body rings not or very slightly vaulted. Prozonae smooth. Metazonae with rather sparse, but well-pronounced striations; 6 striae in a square with sides equal to metazonal length just below ozopore level; a dense whorl of long (equal to or slightly exceeding metazonal length), erect setae at metazonal hind margin. Ozopores placed close (about 1–2 times of their diameter) behind pro-metazonal suture. Telson ( Fig. 21 ) densely setose, dorsal surface evenly covered with very long setae. Preanal process long and slender, pointed, strongly curved downwards, equal to or slightly surpassing longest anal setae. Subanal scale short, flat, tightly fitting under anal valves, bearing several setae. Anal valves densely pilose, with a distinct row of shorter (1/3–1/2 of the lateral) setae along caudal margins; several rounded bumps present near each margin. Male pleurotergum 7 with broad, rounded protrusions, directed ventro-mesad. Male leg-pair 1 short, somewhat converging hooks without tarsal remnants. Male walking legs ( Figs 22–24 ) without adhesive pads or other specialized structures. Tarsus of mid-body leg ca 1.5 times longer than tibia and ca 2 times longer than apical claw.

Penis ( Fig. 25 ): elongated, trapezoidal, with short, diverging apical lobes (al) ending with well-developed terminal lamellae (tl).

Gonopods ( Figs 26–28 ): Rather compact, in situ entirely concealed inside gonopodal sinus, promere covering tip of mesomere, opisthomere outreaching by far both pro- and mesomere. Promere ( Fig. 28 , P in Fig. 26 ) relatively short, rounded, subquadrangular, almost parallel-sided, with a concave posterior surface; apical part bent posteriad, with horizontal rows of small protuberances; parabasal internal lobe (il) short, edgy, with two apical setae; parabasal external lobe (el) oblong, outreaching by far internal one. Flagellum (f) thin, nearly 2 times longer than promere. Mesomere (M in Figs 26 & 27 ) short, with a posteriorly deeply concave middle part; apical surface densely tuberculate. Opisthomere ( Figs 26 & 27 ) with a mostly straight posterior margin, without processes; basal spine (bs) slightly sigmoid, pointing distad; intermediate lamella (l) moderately pronounced, reaching ca 2/3 of opisthomere height; velum (v) unipartite, thin, pointed, slightly bent distad; solenomere (s) subconical, with a blunt apex bearing a row of several minute spine-like filaments (sf) on its posterior side.

Vulva ( Fig. 29 ): Considerably compressed meso-laterally, somewhat asymmetric: mesal valve broader and slightly higher than lateral one, operculum with a more steeply oblique lateral margin. Opening (o) narrow and cleft-like, positioned at ca half of bursal height. 5 setae in a vertical row on each valve. Operculum (op) much higher than bursa, with a narrowly rounded apical margin; 4 vertical rows of 4–5 long setae each in distal part of operculum. Receptaculum seminis consisting of a finger-shaped central tube (ct) not forming a distinct central ampulla (ca) and of a thin, somewhat folded posterior tube (pt) ending into an ovoid posterior ampulla (pa).

Remarks. T. orpheus sp. n. is probably an endogean species considering its small size and an almost colourless body, coupled with the fact that it has not been found in any of the caves in the area, which are generally well-prospected in a biospeleological aspect.

The name “ orpheus ” is the result of a public decision after one month of online voting through the website of the National Museum of Natural History in Sofia (NMNHS). The initiative was on the occasion of the 125th anniversary of the museum in 2014, and aimed at raising awareness of taxonomy and and making people acquainted with taxonomists’ job.

Figures

FIGURES 20 – 25. Typhloiulus orpheus sp. n. holotype (22 & 25), paratype male (21, 23 & 24) and paratype female (20) (NMNHS): (20) habitus, not to scale; (21) telson, lateral view; arrows indicating marginal bumps on anal valves; (22) leg 2; (23) mid-body leg; (24) end-body leg; (25) penis. Abbreviations: al: apical lobe, tl: terminal lamellae. Scale bars of the drawings: 0.2 mm.

FIGURES 26 – 29. Typhloiulus orpheus sp. n. paratype male (NMNHS): (26) left gonopods, mesal view; (27) left meso- and opisthomere, lateral view; (28) right promere, caudal view; (29) right vulva, lateral view (setae omitted, receptaculum seen by transparency, but drawn with solid lines for better emphasis). Abbreviations: bs: basal spine, 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: spine-form filaments, v: velum. Scale bars: 0.2 mm.