Thalassisobates almeriensis, Enghoff, 2013

Enghoff, Henrik, 2013, New montane, subterranean congeners of a littoral millipede, genus Thalassisobates (Diplopoda: Julida: Nemasomatidae), Journal of Natural History 47 (23 - 24), pp. 1613-1625 : 1620-1622

Thalassisobates almeriensis sp. nov.

( Figs 4A, B , 5B )

Material studied

Holotype male SPAIN, Andalucía, Almería, T. M. de Almería, Cueva Nueva , 4 January 2002, P. Barranco and J.G. Mayoral leg. ( ZMUC).

The mouthparts of the unique holotype were not dissected.

Diagnosis

A blind species of Thalassisobates . Differs from the other blind congener, T. ememesensis , in being thicker, and in having more setae on the anterior gonopod coxal processes.

Derivatio nominis

Named after its type locality.

Description

As T. emesesensis , except as follows:

Male 38 + 1 + T, length 11 mm, height 0.87 mm.

Colour of preserved specimen whitish-transparent. Length of metazonital setae 0.13 × body height. Antennae: length 176% of body height, with four apical sensilla, relative length of antennomeres 2–8 (8 = apical sensilla) 20/20/18/18/16/7/3, apical sensilla 3.4 times longer than wide. Legs ( Figure 5B ): length 86% of body height in male, relative length of podomeres (prefemur-claw) 17/23/14/13/20/13. Length of claw = 0.63 × length of tarsus. Claw very slender, length/height ratio 7.4; no accessory claw.

Anterior gonopods ( Figure 4A ) as in T. emesesensis sp. nov., but slenderer and with four setae on each coxal process.

Posterior gonopods ( Figure 4B ) as in T. emesesensis sp. nov.

Habitat

The type locality is a cave situated c. 5 km from the sea at 560 m above sea level ( Ribera et al. 2003). The habitat of T. almeriensis is therefore very different from that of the widespread T. littoralis , just as is the case for T. emesesensis sp. nov.

Notes on T. littoralis

For comparison with the new species, some details of a male from Sweden (ZMUC) are given here:

Male 50 + 2 + T, height 0.57 mm.

Antennae: length 213% of body height, with four apical sensilla, relative length of antennomeres 2–8 (8 = apical sensilla) 17/20/17/18/18/6/3, apical sensilla 3.8 times longer than wide. Legs ( Figure 5C ): length 104% of body height, relative length of podomeres (prefemur-claw) 16/21/12/13/20/18. Length of claw = 0.87 × length of tarsus. Claw very slender ( Figure 5C ), length/height ratio 7.8; no accessory claw.

Gonopod variation: Enghoff (1985) discussed variability of the posterior gonopods of T. littoralis . The anterior gonopods also exhibit variability, notably in the setation of the coxal processes. In the Swedish specimen illustrated in Figure 3B each process carries two stout, curved setae on the posterior surface at about two-thirds of the process’s length from its basis. Exactly the same pattern was illustrated by Schubart (1934: fig. 296), based on a specimen from the same population, and by Blower (1985: fig. 31). However, Silvestri (1903: fig. 7) illustrated a group of five straight setae on each process, also on the posterior surface at about two-thirds of the process’s length from its basis. Verhoeff (1908: fig. 3) showed three straight setae in this position, apparently on the anterior surface of the coxal process (but this could be an error of interpretation – the gonopods are very small). Strasser (1933) found from two to four setae per process in a large series.

Since Enghoff (1985) published a distribution map for T. littoralis , the species has been recorded from a couple of additional countries: Ireland ( Cawley 1997) and Norway ( Meidell and Djursvoll 2005; Djursvoll 2007). Two further European countries can be added to the list based on so far unpublished material: GREECE: Cyclades, Syros Island, Finikas, 14 December 1989, S. Sfendourakis leg., M. Karamaouna det. ( ZMUC), Boeotia, Loukisia , 13 June 1984 (beach), Sette leg. , H. Enghoff det. ( MCSNV); and SPAIN: Galicia, Province of Pontevedra, rocky shore south of Baiona , 1 March 1993, D. T. Bilton leg. , R. D. Kime det. (coll. Kime) .

There are also several additional records from countries from where the species was already known. European records are shown in Kime and Enghoff (in preparation). See http://insects.oeb.harvard.edu/boston_islands/bugmonth/0908_beach_milli.htm for new information on the species’ occurrence in North America.

Figures

Figure 3. (A,C,D) Thalassisobates emesesensis sp. nov., (B) Thalassisobates littoralis. (A, B) Anterior gonopods, posterior view; (C) posterior gonopods, anterior view; (D) right vulva. Scale bars 0.05 mm. bu: bursa, cph: apical hook of coxal process, cps: setae of coxal process (encircled), ff: flagellum-conducting flange with spines, fl: flagellum, mcx: intercoxal muscle, mf: flagellar muscle, op: operculum, rs: receptaculum seminis.

Figure 4. Thalassisobates almeriensis sp. nov. (A) Anterior gonopods and right posterior gonopod, posterior view; (B) left posterior gonopod, posterior view. Scale bars 0.05 mm. cps: setae of coxal process (encircled), fp: basal flap of anterior gonopod telopodite, pg: posterior gonopod.

Figure 5. Thalassisobates spp., midbody legs. (A) Thalassisobates emesesensis; (B) Thalassisobates almeriensis (with sternum); (C) Thalassisobates littoralis. Scale bars 0.1 mm (B), 0.05 mm (A, C).