Serendibia cavernicola Taiti & Checcucci, 2009

Taiti, Stefano & Checcucci, Ilaria, 2009, New species and records of terrestrial Isopoda (Crustacea, Oniscidea) from Socotra Island, Yemen, ZooKeys 31 (3), pp. 73-103 : 81-85

Serendibia cavernicola Taiti & Checcucci , sp. n.

urn:lsid:zoobank.org:act:58F1F669-4AE2-41F2-8C3C-A53B88A8BB6F

Material examined. Socotra: 1 ♁ Holotype, Momi , Kazekas Cave, 12°33'16.8"N 54°18'36.3"E, ca. 500 m, 15.I.2003, leg. S. Taiti & A. K. Nasher, MZUF-9225; 1

♁, 6 ♀♀ Paratypes, same data, MZUF-9225 ; 6 ♀♀ Paratypes, same data, NHCY ( MZUF) .

Additional material. 1 ♁, 1/ 2 spec., Mega 1 Cave, 12°37'37.0"N 53°30'44.2"E, 04.I.2004, leg. E. Claes, MZUF-9226.

Diagnosis. A species of Serendibia characterized by the absence of eyes, elongated body (about 3 times longer than wide), telson with widely rounded apex; antennule with elongated aesthetascs, antenna with fifth article of peduncle not swollen, male pleopod 1 exopod with large triangular posterior point, and endopod with apical part pointed and bent outwards.

Description. Maximum length: ♁, 2.9 mm; ♀, 4.0 mm. Body elongated (about 3 times longer than wide) and colourless (Fig. 1A). Back with scattered long scalesetae (Fig. 1B); each pereionite with one nodulus lateralis per side (Fig. 1C), nodulus lateralis on pereionite 4 more distant from lateral margin than those on the other pereionites, b/c and d/c co-ordinates as in Fig. 1D; no visible gland pores. Cephalon (Fig. 1E,F) about 1.5 times wider than long, with very thin suprantennal line slightly bent downwards in the middle; eyes absent. Pleon narrower than pereion; pleonites without posterior points visible in dorsal view. Telson (Fig. 1G) about twice as wide as long, distal part with straight sides and very broadly rounded apex. Antennule (Fig. 1H) with third article equipped with 2 apical and 3–4 subapical long aesthetascs. Antenna (Fig. 1I) with fifth article of peduncle not swollen; first and third flagellar articles subequal in length, second distinctly shorter; second and third flagellar articles with a row of five and seven aesthetascs, respectively. Buccal pieces as in all the other species of the genus, i.e. mandible with molar penicil simple, maxillule with outer branch bearing 7 simple teeth and inner branch with two short and thickset penicils, maxilliped with endite equipped with a big apical penicil and a long seta on outer corner. Pereiopods with no dactylar seta and with ungual seta flagelliform. Uropod with protopod and exopod grooved on outer margin; insertion of endopod slightly proximal to that of exopod.

Male. Pereiopod 1 ( Fig. 2A) with carpus slightly enlarged. Pereiopod 7 ( Fig. 2B) without particular sexual specializations. Pleopod 1 ( Fig. 2C) exopod with a distinct triangular posterior point bent outwards; endopod with apical part pointed and bent outwards. Pleopod 2 ( Fig. 2D) exopod slightly longer than wide with rounded apex bearing a trifid seta; endopod distinctly longer than exopod. Pleopod 3–5 exopod as in Fig. 2 E-G.

Etymology. Latin cavernicolus = cave-dwelling. The name refers to the locality (Kazekas Cave) where the type specimens were collected.

Remarks. Until now, the genus Serendibia included the type species Serendibia denticulata Manicastri & Taiti, 1987 , from Sri Lanka, and three species from the Socotra Archipelago, i.e. S. vagans and S. filiformis from Socotra Island, and S. samhaensis from Samha Island. The new species from Kazekas Cave described here belongs to the group of Serendibia from the Socotra Archipelago, characterized by the absence of eyes, the colourless body and shape of the endite of maxilliped which has a long seta on the outer corner. The specimens from Mega 1 Cave show some small

I H C

Figure |. Serendibia cavernicola sp. n. ♀ from Kazekas Cave: A Adult specimen, dorsal view B Dorsal scale-seta C Right side of pereion showing disposition of noduli laterales D Co-ordinates of noduli laterales E Cephalon, frontal view F Cephalon, dorsal view G Pleonite 5, telson and left uropod H Antennule. ♁ from Kazekas Cave I Antenna.

84 Stefano Taiti & Ilaria Checcucci / ZooKeys 31: 73–103 (2009)

A B C D E F G

differences from the population of the type-locality (Kazekas Cave) in having shorter and thicker aesthetascs of the antennule ( Fig. 3A ), the male pereiopod 1 carpus more enlarged ( Fig. 3B ), the male pleopod 1 endopod with longer and thinner apical part ( Fig. 3C ), and the male pleopod 2 endopod shorter ( Fig. 3D ) when compared with the exopod. With only one male examined from Mega 1 Cave, it is difficult to judge the importance of these differences, but considering the very similar shape of the male pleopod 1 exopod (compare Fig. 2C and 3C ), we prefer to include also these specimens in S. cavernicola .

The new species is readily distinguishable from all the other Socotran species in the genus by having the body proportionally wider (only 3 times instead of> 4.5 longer than wide), antenna with the fifth article of the peduncle not swollen and more numerous number of aesthetascs on the flagellum. It also differs from S. vagans in the suprantennal line bent down instead of straight, the male pereiopod 1 carpus enlarged, and longer posterior point of the male pleopod 1 exopod; from S. filiformis in thinner and longer aesthetascs of the antennule, the male pleopod 1 exopod with triangular instead of rounded posterior point, and the male pleopod 2 endopod longer in comparison with the exopod. For the enlarged male pereiopod 1 carpus and the similar shape of the male pleopod 1 exopod, S. cavernicola seems to show closest affinities with S. samhaensis , from which it is distinguished by the distal part of male pleopod 1 endopod which is not enlarged and not equipped with flattened setae.

Family Bathytropidae

Figures

Figure 3. Serendibia cavernicola sp. n. ♁ from Mega 1 Cave A Antennule B Pereiopod 1 carpus C Pleopod 1 D Pleopod 2.