Penthesilenula aotearoa (Rossetti et al., 1998)

Pinto, R. L., Rocha, C. E. F. & Martens, K., 2010, On the genus Penthesilenula Rossetti and Martens, 1998 (Crustacea, Ostracoda, Darwinulidae) from (semi-) terrestrial habitats in São Paulo State (Brazil), with the description of a new species, Journal of Natural History 38 (20), pp. 2567-2589 : 2581-2583

Penthesilenula aotearoa (Rossetti et al., 1998)

(figures 3A–D, 6G–M)

Material investigated

(1) Boracéia Biological Station, Municipality of Salesópolis, São Paulo State, Brazil. GPS co-ordinates: 23 ‡ 38’16.9@S, 45 ‡ 50’24.5@W. Inside the forest, near a swamp called Pedreira.

Leaf litter at the foot of a rock wall, water was dripping from it: three ovigerous dissected females with valves prepared for scanning electron microscopy and soft parts mounted in permanent slides ( MZUSP15871–15873 ); seven ovigerous females not dissected, prepared for scanning electron microscopy ( MZUSP15874–15880 ); 287 females kept in toto in ethanol ( MZUSP15881 ). Material collected on 22 September 2001 by CEFR, RLP and KM .

(2) Tamoios road, near Paraibuna, São Paulo State, Brazil. GPS co-ordinates: 23 ‡ 34’26.3@S, 45 ‡ 29’18.2@W. Spring on a rock beside the road.

Wet moss: one ovigerous dissected female with valves prepared for scanning electron microscopy and soft parts mounted in permanent slides ( MZUSP15882 ); three ovigerous females prepared for scanning electron microscopy ( MZUSP15883– 15885 ). Material collected on 4 February 2000 by CEFR .

Abbreviated diagnosis

Medium-sized darwinulid, with elongated, ovoid-shaped Cp. LV w RV on all sides; LV with posterior and antero-ventral tooth; Cms consisting of ca nine clearly separated spots, arranged in a nearly circular rosette. A2 exopodite with two long, subequal setae and one short lateral spine; first segment of A2 endopodite with two ventro-apical setae, y1 a true aesthetasc with rounded tip. Md-palp with setae z and y subequal, reaching almost to tip of terminal claws. Caudal ramus a long seta; P-abd absent.

Description

Cp (figure 6G–L). Rather bulbous, posteriorly widened, forming a brooding pouch; in dv, maximum width situated at about three-fifths of the length, posterior end broadly rounded, anterior gently pointed; maximum height in lv situated at the posterior third; posterior margin more broadly rounded than anterior margin, dorsal margin distinctly slanting forward, both valves rather elongated. Calcified inner lamellae absent; hinge adont. Internally, LV with large ventroanterior tooth, situated rather ventrally, and caudal tooth.

A1 (figure 3A, 6M). First segment carrying two dorsal setae; second segment shorter, carrying three ventral setae, two subequal and one longer directed backwards, and one small dorso-apical seta. Third segment with two apical setae, one dorsal (s1) and one ventral. Fourth segment with two long dorsal setae (s2 and s3) and a shorter one ventrally. Fifth segment with four apical setae, two subequal ventral setae and two longer, unequal dorsal setae. Sixth article with sub-apical dorsal aesthetasc, and two apical setae of different length, the dorsal one ca twice the length of the ventral one. Last three segments with dorso-apical a -setae.

A2 (figure 3B). Protopodite two-segmented; first segment with two ventral setae and a sturdy dorsal hook; second segment dorsally bearing distal seta. Exopodite with two sub-equal setae and one smaller, lateral spine. Endopodite three-jointed; first podomere with ventro-proximal group of four aesthetascs (Ac) and two ventro-distal setae on enlarged corner; second podomere with G3 a typical darwinulid seta, morphologically in between a claw and a seta, G1 a large claw, G2 a short claw, about half the length of G1, z1 a long claw, equalling G 1 in size, z2 a short claw, but longer than G2, z3 a short but stout seta; third podomere inserted into the second one in sub-apical position, with one aesthetasc (y3) ventrally and two distal claws (Gm and GM) of different length.

Md-palp (figure 3C). Three-segmented, composed of basis and two-jointed endopodite; first article of the endopodite distally widened, bearing two long internal, subequal setae (y and z), reaching almost the tips of the terminal claws, and two shorter, sub-equal setae, one median (x) and one external (w); second article incompletely divided in some specimens, with two medial setae (a and b) inserted near the additional division along the external edge and distally with five hirsute claws of different length and one small, internal seta (c).

Mx1, T 1–3 (not illustrated). As typical of the genus.

Caudal ramus and abdomen (figure 3D). Caudal ramus a long seta, slightly widened in the proximal portion. Postabdomen absent.

Measurements

LV: Le~481–537 M m (N ~5), H~230–260 M m (N ~5). RV: Le~466–506 M m (N ~2), H~217–229 (N ~2).

Ecology and distribution

The species occurred in extremely large numbers in wet leaf litter at the foot of a rock wall in Boracéia forest, but was also found in nearly every sample of semiterrestrial habitats thus far taken in São Paulo State. This wide occurrence agrees well with the high salinity and temperature tolerance of this species as demonstrated by Van Doninck et al. (2003).

Penthesilenula aotearoa was thus far only known from New Zealand, where it had been described from a small swamp near a stream. This is the first time it has been recovered outside of New Zealand. The specimens from Brazil are most similar to those from New Zealand. Soft part morphology is identical and valves are just a little more elongate and show a slightly different shape in the caudal part. It will be most interesting to see from genetic screening how distant both groups of populations are from each other and for how long they have been separated.