Strandesia sanoamuangae, Savatenalinton & Martens, 2010

Savatenalinton, Sukonthip & Martens, Koen, 2010, On the subfamily Cypricercinae McKenzie, 1971 (Crustacea, Ostracoda) from Thailand, with the description of six new species 2379, Zootaxa 2379, pp. 1-77 : 18-22

Strandesia kraepelini (G.W. Müller, 1906) ( Figs 9–11)

1906 Cypris kraepelini G.W. Müller : 139, Pl. 1, Figs 1–7

1912 Strandesia kraepelini — G.W. Müller: 190.

Material examined. Many females from several samples (see Table 1).

Diagnosis. Carapace in lateral view subovate, greatest height situated in front of mid-length, anterior margin broadly rounded, posterior margin more narrowly rounded; valve surface weakly tuberculated; carapace in dorsal view subelliptical, greatest width situated at mid-length; LV overlapping RV along anterior, ventral and posterior margins; LV with internal groove along valve margin, without inner list; Wouters organ on A1 small, Rome organ long, aesthetasc ya on terminal segment shorter than short apical seta on A1; aesthetasc Y on A2 long; d seta on T1 present; caudal ramus stout, length of distal claw c. half of that of ramus, distal seta c. half of that of distal claw, proximal seta reaching tip of ramus; caudal ramus attachment stout, with Triebel’s loop situated at middle of distal part of main branch, dorsal and ventral branches well-developed.

Differential diagnosis. Strandesia kraepelini ( Müller, 1906) is similar to S. complexa Victor & Fernando, 1981 . It can be distinguished by the absence of lip-like flange on anterior margin of LV, wider rounded posterior margin, weakly tuberculated valve surface and longer distal claw of ramus.

For distinctions between S. kraepelini , S. perakensis and S. sanoamuangae sp. nov., see description of the latter species above.

Measurements (in µ m). LV (n=2), L=755–763, H=423–438; RV (n=2), L=736–738, H=415–436; Carapace (n=2), L=757–772, W=403–405.

Ecology. This species is thus far recorded from diverse ecological habitats, ranging from lakes, ponds, ricefields, man-made reservoirs, mining pools, marshes, streams, swamps, irrigation drainage to roadside canals and natural springs ( Victor & Fernando 1981b; this study). It was found in a pH range of 6.50–7.50 and a temperature range of 22.5–38.3° C.

Abbreviated redescription of female. Carapace in lateral view ( Fig. 9A) subovate (length c. 1.75 times height), dorsal margin arched, ventral margin somewhat straight, greatest height situated in front of midlength, anterior margin broadly rounded, posterior margin more narrowly rounded; valve surface weakly tuberculated.

Carapace in dorsal view ( Fig. 9B) subelliptical, greatest width situated at mid-length; LV overlapping RV along anterior, ventral and posterior margins.

Carapace in ventral view ( Fig. 9C) subelliptical, ventral margin slightly sinuous at mid-length.

LV in interior view ( Fig. 9D) subovate, with groove along valve margin, dorsal margin arched, ventral margin slightly sinuous, greatest height situated in front of mid-length, anterior margin broadly rounded, posterior margin rounded, with slightly pointed edge at mid-height; calcified inner lamella wide anteriorly, without inner list, posteriorly more narrow.

RV with shape generally as in the LV, except for the continuously rounded posterior margin; in interior view ( Fig. 9E) without selvage; inner lamella without inner list.

A1 ( Fig. 10A): first segment with small proximal Wouters organ and two subequal ventro-apical setae; second segment with a long Rome organ and short dorso-apical seta; aesthetasc ya on terminal segment shorter than short apical seta.

A2 ( Fig. 10B–C): exopodite with longest seta reaching tip of first endopodal segment; first endopodal segment with long aesthetasc Y, natatory setae long (longest setae almost reaching tips of claws), length of shortest seta c. 1/4 of that of penultimate segment, ventro-apical seta long (reaching tip of terminal segment); penultimate segment distally with three serrated claws (length c. 1.4 times of that of penultimate segment), aesthetasc y2 long (reaching beyond tip of terminal segment); terminal segment with two serrated claws, long g seta and aesthetasc y3, the latter c. 2/3 of accompanying seta.

Lateral subapical seta on basal segment of Mx1-palp short ( Fig. 11A), one of two large bristles on third endite smooth, sideways directed setae on first endite unequal, short one c. half of long one.

T1 ( Fig. 10G–H) with a-, b- and d-setae all present.

T2 ( Fig. 11B) with d1 c. twice the length of d2.

Caudal ramus ( Fig. 11F) stout, with ventral margin weakly serrated, distal and proximal claws long, serrated, length of distal claw c. half of that of ramus, distal seta short (c. half of that of distal claw), proximal seta long (reaching tip of ramus). Caudal ramus attachment ( Fig. 11E) stout, with Triebel’s loop situated at middle of the distal part of the main branch, dorsal and ventral branches well-developed.

Male unknown.

Remarks. Strandesia kraepelini (G.W. Müller, 1906) was described from Java by G.W. Müller (1906). Victor & Fernando (1981b) reported this species from Malaysia and Indonesia. In this study, we found this species in several localities in Thailand. The morphology of valves and soft parts of Thai specimens are congruent with those of Malaysian and Indonesian specimens except for two features: 1) while both large bristles on third endite of Mx1 are smooth in Malaysian and Indonesian specimens, there are one smooth and one slightly serrated in Thai specimens; 2) the dorsal subapical seta on the first segment of the A1 is absent in the Thai material, whereas this seta was not mentioned in previous papers.