Penthesilenula brasiliensis ( Pinto and Kotzian, 1961 )

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 : 2573-2577

Penthesilenula brasiliensis ( Pinto and Kotzian, 1961)

(figures 1A–F, 5A–K)

Investigated material

From three localities at the Boracéia Biological Station, Municipality of Salesopólis, São Paulo State, Brazil:

(1) 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 with dripping water: 14 ovigerous dissected females with valves prepared for scanning electron microscopy and soft parts

mounted in permanent slides ( MZUSP 15886–15899); nine ovigerous females not dissected, prepared for scanning electron microscopy ( MZUSP 15900–15908); 127

females kept in toto in ethanol ( MZUSP 15909).

(2) GPS co-ordinates: 23 ‡ 40’00.7@S, 45 ‡ 54’08.9@W. Inside the forest, near a location formerly used for extracting sand, beside the road of the Guaratuba river.

Soil from dried-up puddles (but still with humidity): seven ovigerous females prepared for scanning electron microscopy ( MZUSP15910–15916 ); 16 females kept in toto in ethanol ( MZUSP15917 ) .

Mosses on fallen tree trunks: one ovigerous female prepared for scanning electron microscopy ( MZUSP 15918).

(3) GPS co-ordinates: 23 ‡ 39’12.2@S, 45 ‡ 53’24.4@W. Inside the forest, close to Venerando stream.

Humus inside a decaying tree trunk, lying on the ground: one ovigerous female prepared for scanning electron microscopy ( MZUSP 15919).

Material collected on 22 September 2001 by C. E. F. Rocha ( CEFR), R . L. Pinto ( RLP) and Koen Martens ( KM) .

Diagnosis (modified from Rossetti and Martens, 1998)

Valves relatively short and high, LV w RV on all sides, LV with (sometimes very) small antero-ventral and large postero-ventral internal teeth. Cms a rosette of ca nine relatively large scars.

First segment of A1 with two subequal, dorsal setae; second segment with short dorso-apical seta and three ventral setae, two shorter, subequal and one long (the latter ca three times as long as the former ones); third segment with dorsal (s1) and ventral seta; fourth segment with two dorsal setae (s2 and s3) and ventral seta; s2 the longest of the three s-setae, ventro-apical seta on third segment longer than that on fourth segment, reaching beyond edge of fourth segment. A2 exopodite with two unequal setae (shorter one ca two-thirds of longer one) and lateral, conical spine. Penultimate segment of Md-palp with setae y and z both long, reaching beyond mid-length of the longest apical claws on the next segment; last segment with five apical claws and three setae, internal seta c short, subapical, external setae a and b long, reaching beyond halfway the largest claw, seta b the longest. Caudal ramus a long seta. P-abd absent.

Description

Cp (figure 5A–K). Valves relatively short and high, LV w RV on all sides, dorsal margin straight, ventral margin slightly sinuous, posterior margin broadly rounded, nearly straight, anterior margin asymmetrically produced towards the ventral side, more pointed in the larger nominal than in the smaller form. RV without postero-ventral keel, LV with small antero-ventral (difficult to see in the larger, nominal form) and large postero-ventral internal teeth. Anterior inner lamella developed in nominal form, absent in smaller form. Hinge adont. Cms a rosette of ca nine relatively large scars.

A1 (figure 1A). First segment stout with two dorsal setae; second segment bearing three ventral setae: two shorter, subequal and one long (the latter ca three times as long as the former); third segment with ventral seta and dorsal seta s1; fourth segment with two dorsal setae (s2 and s3), s2 being the longest of the three s-setae, ventro-apical seta on third segment longer than that on fourth segment, reaching beyond edge of fourth segment; fifth podomere bearing four apical setae, two shorter, subequal ventral setae and two longer ones in dorsal position; last podomere with subapical aesthetasc and two apical setae, the ventral one about half the length of the dorsal one; last three segments of endopodite with dorso-apical a -setae.

A2 (figure 1B). Protopodite biarticulated, first segment with two ventral setae and a dorsal hook (h), second segment with long, dorsal seta. Exopodite (exo) situated dorsally, with two apical setae, one long, the second about two-thirds of

the length of the former, and a lateral, conical spine. Endopodite three-segmented; first podomere with ventral aesthetasc clump (Ac) in proximal position and two setae on the expanded ventro-apical corner; second podomere with medio-ventral aesthetasc y1 seta-like, distally pointed, aestetasc y2 ventro-apically positioned, with rounded tip; distal chaetotaxy with aesthetasc y3 relatively large, with rounded tip, G3 a medium-large, seta-like claw, hirsute in the distal three-quarters, G1 a large claw, G2 the shortest claw, z1 a large claw, equal to G1, z2 a short claw, z3 a short and stout seta; third podomere short and stout, with ventral aesthetasc (y3) and two apical claws, one shorter (GM), about two-thirds of the length of the larger one (Gm).

Md-palp (figure 1C). Three-segmented, consisting of basis and two-segmented endopodite. First podomere of endopodite distally widened, with external, subapical seta w and three apical setae: one median x about half the length of the external ones, and two long lateral ones of subequal length y and z, the latter reaching halfway beyond the largest apical claws on the next segment; second podomere narrow, with five apically hirsute, unequal claws, one short internal seta c, and two subapical, external setae a and b, the latter subequal, b being the longest and reaching beyond the middle of the largest claws.

Mx1 (not illustrated). Proximal segment of palp with lateral, subapical seta, a group of four terminal setae, two straight and two curved and plumose, and

one seta inserted close to the articulation with the terminal segment. Terminal segment of palp with short and thin median seta flanked by two stout setae dis-

tally provided with a double row of setulae, the latter about four times as long as the former one.

T 1 (not illustrated). Protopodite with two setae near the articulation with the endopodite, one short and one long, both plumose. Three-jointed endopodite; first segment with two subequal, subapical setae; second segment with subapical seta; third segment with two lateral setae and a terminal claw.

T 2 (not illustrated). Strongly chitinized. One-segmented protopodite with short, ventral seta and two subapical setae, one about half as long as the other. Endopodite four-articulated; first segment bearing three setae, two shorter, subequal, one longer, slightly exceeding the length of next segment; second and third segment with a ventro-apical seta each; last segment provided with strong terminal claw and two lateral setae, the ventral one longer than the dorsal one.

T 3 (figure 1E). Strongly chitinized, but slightly more slender than T 2. Protopodite one-segmented and short, with two ventro-apical setae. First three endopodial segments with a ventro-apical seta each; last segment bearing a long, curved terminal claw, and two subapical setae, one dorsal and one ventral, the latter longer. An aberrant T 3 ( MZUSP 15887—figure 1D) with one endopodal segment missing, apical segment with only one claw, second claw and lateral seta missing, occurred in one individual.

Caudal ramus and abdomen (figure 1F). Caudal ramus with long and slender seta. Postabdomen absent.

Measurements

Pinto and Kotzian (1961): Le~ 0.47–0.55 mm, H~ 0.21–0.28 mm, W~ 0.22 mm.

Martens et al. (1997): Le~490–508 M m (N ~3), W~233–239 M m (N ~2), H~245 M m (N ~1).

This paper: (a) nominal form (see below): Le of Cp right lateral view: 484–515 M m; H of Cp right lateral view: 238–251 M m, Le:H~2.02–2.13 (N ~7); (b) smaller form (see below): Le of Cp right lateral view: 402–447 M m; H of Cp right lateral view: 204–233 M m, Le:H~1.94–2.00 (N ~3).

Ecology and distribution

Penthesilenula brasiliensis s. l. was thus far known from lakes and rivers, as well as from interstitial habitats. Here, it is for the first time recorded from truly terrestrial habitats (see below). Penthesilenula brasiliensis is known from all continents, except North America and Antarctica, but it is almost certain that, although it is rare and mostly occurs at low densities, it has a cosmopolitan distribution. In Brazil, it was previously recorded from Rio Grande do Sul ( Pinto and Kotzian, 1961; Würdig, 1983, 1984).

Taxonomic remarks

This species was first described as a subspecies of Darwinula (now Penthesilenula ) africana Klie, 1935 , but Martens et al. (1997) raised it to specific rank. Penthesilenula africana has also been reported from Brazil (São Jose´: Klie, 1940), but not yet from the State of São Paulo. This species has not been found since Klie reported it from both Africa and Brazil and its status is actually doubtful. Penthesilenula africana and P. brasiliensis differ in aspects of chaetotaxy, and these features (e.g. absence of seta c on mandibular palp) might actually be due to an incomplete original description of P. africana .

The different populations thus far allocated to P. brasiliensis are all highly similar in soft part anatomy, but show a significant variability in valve morphology. Four main lineages can be distinguished:

(1) The nominal P. brasiliensis , which is relatively large (Le~ 0.47–0.55 mm) and subrectangular (Le:H: 2.02–2.13), with narrowly produced anterior margin, small antero-ventral tooth in the LV, a wider inner lamella than in the other lineages and a wider LV w RV overlap. Occurrence: (semi-) terrestrial and in riverine pools, Brazil.

(2) A smaller (Le~ 0.40–0.45 mm) and more rectangular form (Le:H~ 1.94–2.00), with more broadly rounded anterior margin, a small anteroventral tooth in the LV, a narrow inner lamella and a less pronounced LV w RV overlap. Occurrence: (semi-) terrestrial, Brazil.

(3) A larger form (Le~ 0.49–0.51 mm), but morphologically identical to the previous one. Occurrence: in lakes in Ireland, interstitially in southern France. (see figure 2 in Martens et al., 1997 and figure 29 in Rossetti and Martens, 1998).

(4) A smaller form (Le~ 0.419 –0.455 mm), slightly more elongated than the previous one, but with similar anatomy. Occurrence : streams in Drakensberg area, 1000–2000 m a.s.l., South Africa (see figure 29 in Rossetti and Martens, 1998) .

The evolutionary significance of this variability is discussed below.