Thassoblaniulus radjai Antić & Enghoff, 2015

Antić, Dragan Ž., Mock, Andrej & Enghoff, Henrik, 2015, Two new species of the millipede family Blaniulidae (Diplopoda, Julida) from caves in central and southeastern Europe, Zootaxa 3985 (4), pp. 523-540 : 529-536

Thassoblaniulus radjai Antić & Enghoff , sp. n.

Figs 13–33

Material studied. Holotype male ( ZMUC): Shpella e Zezë (Shpella e Pëllumbasit, Black Cave), village of Pëllumbas, near Tirana, Albania, 0 3.08.2003, leg. T. Rađa. Paratypes ( ZMUC, IZB): two adult males (one with lost gonopods), seven juvenile males and 13 females: same data as holotype.

Etymology. The new species is named after Tonći Rađa, a well-known Croatian speleologist who discovered numerous new cave animals.

Diagnosis. Differs from Thassoblaniulus simplarius (see Table 2 ) and all other blaniulid species by the shape of the distal part of the anterior gonopod coxal processes, which are characterised by very broad lateral shoulders and axe-like postero-mesal flanges.

Description. Holotype male: L 10 mm, H 0.6 mm, paratype adult male: L 11 mm, H 0.65 mm; paratype adult male (with lost gonopods): L 13 mm, H 0.7 mm, females up to L 15 mm, H 0.78 mm. Number of body rings: holotype male: 31 podous + 2 apodous + telson; paratype adult male: 34 podous + 2 apodous + telson, paratype adult male (with lost gonopods): 36 podous + 2 apodous + telson, juvenile males: 26–37 body rings + telson (including 1–4 apodous rings), females: 28–47 body rings + telson (including 1–5 apodous rings).

Colour. Yellowish white to pale brown. Some specimens with clearly visible, large and darker ozadenes.

Head. With one row of a very small number of ocelli on each side. Holotype and paratype adult males with 2+2 ocelli, paratype adult male (with lost gonopods) with 4+4 ocelli, juvenile males and females with 2–4 ocelli on each side (2+2, 2+3, 3+2, 3+3, 3+4, 4+3, 4+4). Length of antennae 169 % of H in paratype male, 130 % of H in female. Relative lengths of antennomeres 1–8 (8 = apical sensilla): 7/19/18 /15/ 20/14/5 /2 % in paratype male, 8/17/ 15 /17/ 20/14/5 / 4 in female. In males, mandibles with usual parrot-bill-like modification of cardo and stipes.

Midbody rings with ca. 14 short setae on posterior margin, length of setae ca. 6 % of H in paratype male, 5 % of H in female. Latero-ventral sides of the rings with longitudinal striations which extend into prozonites.

Legs: length 92 % of H in paratype male, 77 % of H in female. Relative lengths of podomeres from coxa to claw 16/ 14/17/10 / 10/21/12 % in paratype male, 15/ 15/17/9 / 9/22/13 % in female; claw length/height 6 in paratype male and female. No accessory claw. Lanceolate setae present on femur (1), postfemur (2) and tibia (2) in paratype male.

First pair of male legs ( Figs 23, 24 and 31 ) simple, with six short podomeres. Division between tibia (ti) and tarsus (ta) incomplete and poorly visible. Prefemur with one long ventral seta. Tarsus with a rudimentary double claw (cl) on a small knob.

Second pair of male legs ( Figs 25 and 32 ) with one and two ventral, lanceolate setae (ls) on postfemur and tibia.

Penis ( Figs 25 , p and 29) in the form of a high isosceles subtriangle or triangle, gradually tapering from base to top, apically truncate or completely acuminate.

Ventral margin of segment 7 in males ( Fig. 26 ) with a stout ridge, but without a horizontal mesad flange.

Anterior gonopods ( Figs 13–16 , 27 and 28 ) with very distinctive, separated coxal processes (cp) which are widest at base. From base to top, in the middle part, lateral margins first slightly converging and then slightly diverging. In the apicalmost ⅓, lateral margins suddenly narrowing, forming lateral shoulders (lsh) and very narrow tips when seen in oral or caudal view. In lateral view, the apical part with very characteristic axe-like postero-mesal flanges (f). Telopodites (t) short, ca. ¼ - ⅓ the length of coxal processes; without setae; somewhat curved orally; almost of the same width over the entire length and with a rounded tip or with lower mesal side of tip, from the posterior view.

Posterior gonopods ( Figs 17 –22 and 30) simple and elongated. Lateral view: arched (or S-shaped); first ⅔ of almost constant width, with somewhat narrower second ⅓. Border between second and third ⅓ is the narrower part. The last third is the widest part, in the form of a wide leaf-shaped lamella (ll) with numerous minute setules and microspines (Fig. 22). Lamella laterally with a tubular solenomere (so) ( Fig. 21 ). In situ the leaf-shaped lamellae fit nicely with the narrow distal parts of anterior gonopods on the both sides. Antero-posterior view: second ⅓ is the widest, gradually tapering to very narrow part, the beginning of the lamella.

Second pair of female legs without any peculiarities.

Vulvae ( Fig. 33 ) ellipsoid, with somewhat longer operculum (o). Both operculum and bursa (b) without setae. Receptaculum seminis (rs) single, ellipsoid. Vulval invaginations reaching back to ring four.

Note on cave adaptations. Although the new species has so far been found only in a cave, it is not a real cavedweller. Evidence for this claim includes the pigmented, mainly pale brown body (a few specimens are with brighter coloration which may indicate that they were caught shortly after molting), short setae on metazonites, “normal” length of walking legs and antennae as well as presence of ocelli. The number of ocelli is reduced to 2–4 on each side of the head, which may be interpreted as one step towards troglomorphism. Probably T. radjai sp. n. is a troglophilic species.

Distribution. Known only from the type locality (cave) near Tirana, Albania ( Fig. 43 , yellow triangle).

Figures

FIGURE 33. Thassoblaniulus radjai sp. n., female vulva, lateral view. b: bursa, o: operculum, rs: receptaculum seminis. Scale line: 0.05 mm.

FIGURE 43. Distribution of the genera Cibiniulus Verhoeff, 1897 and Thassoblaniulus Mauriès, 1985.

FIGURES 13 – 16. Thassoblaniulus radjai sp. n., paratype male anterior gonopods. 13. anterior view; 14. lateral view; 15. posterior view; 16. distal view. f: postero-mesal flange, t: telopodite, cp: coxal processes, lsh: lateral shoulder. Scale lines: 0.1 mm.

FIGURES 17 – 20. Thassoblaniulus radjai sp. n., paratype male posterior gonopod tip. 17. lateral view; 18. anterior view; 19. mesal view; 20. posterior view. – ll: leaf-shaped lamella, so: solenomere. Scale lines: 0.1 for 17, 18 and 19; 0.05 mm for 20.

FIGURES 21 and 22. Thassoblaniulus radjai sp. n., paratype male posterior gonopod. 21. solenomere; 22. detail of lamella. Scale lines: 0.01 mm.

FIGURES 23 – 26. Thassoblaniulus radjai sp. n., paratype male. 23. first pair of legs, antero-lateral view; 24. first pair of legs, anterior view; 25. second pair of legs with penis, posterior view; 26. body ring 7, ventral view. – p: penis, cl: claw, ls: lanceolate seta, ta: tarsus, ti: tibia. Scale lines: 0.1 mm.

FIGURES 27 – 32. Thassoblaniulus radjai sp. n., holotype male. 27. anterior gonopods, posterior view; 28. anterior gonopods, lateral view; 29. penis, posterior view; 30. posterior gonopod, lateral view; 31. first pair of legs, posterior view; 32. second leg. Scale line: 0.4 mm.

Tables

TABLE 2. Differences between Thassoblaniulus simplarius Mauriès, 1985 and T. radjai sp. n.

Characters	Thassoblaniulus simplarius Mauriès, 1985	Thassoblaniulus radjai sp. n.
Ocelli	♂♂ 3–6, ♀♀ 4–7; one or two rows	2–4 in both sexes; one row
L and H of body (mm) Length/height ratio of claws of midbody legs	♂♂ 6–10 L, 0.35–0.6 H ♀♀ up to 13 L, 0.7 H 4	♂♂ 10–13 L, 0.6–0.7 H ♀♀ up to 15 L, 0.78 H 6
First pair of legs in ♂♂	Without claws	With duble claws
Telopodites of anterior gonopods	Less than ¼ the length of coxal processes	ca. ¼ to ⅓ of length of coxal processes
Lateral margins of distal parts of anterior gonopods Postero-mesal flange of anterior gonopods	Gradually tapering to the top Bilobed	Suddenly getting narrow, forming lateral shoulder Axe-like
Basal part of anterior gonopods	Low	High
Posterior gonopods in lateral view	With narrow basal part which gradually widens up to leaf-shaped lamella	With somewhat broader basal part which gradually tapers up to the leafshaped lamella