Pseudostrandesia gaetani, 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 : 30-35

Pseudostrandesia gaetani sp. nov. ( Figs 19–21)

Holotype. A female, with soft parts dissected in glycerine in a sealed slide and valves stored dry in a micropalaeontological slide (O.C.3133).

Paratypes. Three dissected females ( MSU-ZOC.037, MSU-ZOC.039, MSU-ZOC.040) stored as the holotype, four undissected females (O.C.3134, MSU-ZOC.035, MSU-ZOC.036, MSU-ZOC.038) stored dry in micropalaeontological slides after use for SEM and several females in 70% EtOH .

Repository. The holotype and one undissected paratype are deposited in the Ostracod Collection of the R. B.I.N.Sc. Two dissected and two undissected paratypes and several undissected paratypes in EtOH are deposited in the Natural History Museum , MSU (Mahasarakham, Thailand) .

Type locality. Nong Naree swamp, Muang district, Phetchabun Province, 28 September 2005, coordinates: 16° 26´23.7˝ N and 101° 08´29˝ E (TH051). Accompanying ostracod fauna: Bradleycypris vittata ( Sars, 1903) , Bradleytriebella decorata ( Sars, 1903) , Chrissia sp. , Hemicypris exigua Broodbakker, 1983 , Physocypria sp.3 , Pseudostrandesia calapanensis ( Tressler, 1937) , P. mamarilorum (Victor & Fernando, 1981) , P. phetchabunensis sp. nov., P. thailandensis sp. nov., Sarscypridopsis sp. , Strandesia kraepelini ( Müller, 1906) .

Other localities. Roadside canal, Wat Boht district, Phitsanulok Province, 26 September 2005, coordinates: 17° 01´51.7˝ N and 100° 18´49.6˝ E (TH042). Accompanying ostracod fauna: Bradleystrandesia weberi ( Moniez, 1892) , Cypretta sp. , Physocypria sp. , Pseudostrandesia mamarilorum (Victor & Fernando, 1981) , P. ovata sp. nov., Stenocypris sp.

Etymology. The new species is named after Prof. Dr. Gaetan Borgonie (Ghent University, Ghent, Belgium) in appreciation of his friendship and encouragement over the years.

Diagnosis. Carapace in lateral view elongated, with highest point at mid-length; valve surface ornamented with dispersed long setae and with a few small pustules at anterior part; carapace in dorsal view with beak-like anterior extremity; LV with internal groove along valve margin, inner lamella with one inner list; RV with large marginal selvage; A1 with long Rome organ, long Wouters organ, aesthetasc ya slightly shorter than short apical seta; A2-penultimate segment divided; d seta on T1 absent; caudal ramus slender, distal seta as long as proximal claw; caudal ramus attachment with Triebel’s loop situated at middle of distal part of main branch, dorsal branch short, ventral branch well-developed.

Differential diagnosis. Pseudostrandesia gaetani sp. nov. is characterized by the beak-like anterior extremity in dorsal view. It cannot be confused with any other species in Pseudostrandesia .

Measurements (in µ m). LV (n=3), L=741–826, H=419–465; RV (n=3), L=737–807, H=416–455; Carapace (n=2), L=806–822, W=417–437.

Ecology. This species is thus far recorded from 2 localities: a swamp and a roadside canal. It was found in a pH of 6.79–6.92 and temperatures of 27.6–31.2° C.

Description of female. Carapace in lateral view ( Fig. 19A) elongated (length c. twice the height), anterior and posterior margins rather narrowly rounded, dorsal margin bluntly arched, greatest height situated at midlength, ventral margin straight; external valve surface set with dispersed long setae and a few small pustules (Porenwarzen) at anterior part. In interior view, the valves show traces of a pit-like ornamentation.

Carapace in dorsal view ( Fig. 19C) subovate, with beak-like anterior extremity, rounded posterior extremity, greatest width situated slightly behind mid-length; LV overlapping RV along anterior, ventral and posterior margins.

Carapace in ventral view ( Fig. 19D) with LV overlapping RV at anterior side, ventral margin of LV sinuously protruding at c. mid-length.

Carapace in posterior view ( Fig. 19B) with symmetrical position of both valves.

LV in interior view ( Fig. 19E) with markedly inwardly displaced groove along valve margin, dorsal margin arched, greatest height situated at mid-length, sloping down to anterior and posterior rounded margins, ventral margin slightly sinuous; calcified inner lamella wide anteriorly, with one prominent inner list, posteriorly more narrow.

RV in interior view ( Fig. 19F) with incompletely developed selvage along anterior margin; ventral margin slightly sinuous in front of mid-length; inner lamella without inner list, anteriorly wider than posteriorly.

A1 ( Fig. 20A) short and stout, first segment with relatively long dorso-subapical seta (reaching beyond tip of segment) and two long subequal ventro-apical setae, proximal Wouters organ long, tube-like. Second segment slightly wider than long, with one short dorso-apical seta and long Rome organ ( Fig. 20B). Third segment bearing two (one dorso-, one ventro-) apical setae, the former long (reaching beyond end of fifth segment), the latter shorter (reaching beyond end of fourth segment). Fourth segment with two long dorsal setae and two shorter ventral setae (length of shortest c. half of that of fifth segment). Fifth segment dorsally with two long setae, ventrally with two (one long, one short) setae, the short one reaching beyond tip of the penultimate segment. Penultimate segment with four long setae. Terminal segment with three (two long, one short) apical setae and an aesthetasc ya, the latter shorter than the short apical seta.

A2 ( Fig. 20C–D): exopodite with three (one long, two short) setae, the long one reaching tip of first endopodal segment. First endopodal segment with long natatory setae (reaching beyond tips of end claws), length of shortest seta less than half of that of the penultimate segment, aesthetasc Y long, ventro-apical seta long (reaching beyond tip of terminal segment). Penultimate segment divided, distally with three serrated claws (length c. 1.4 times penultimate segment) and with long aesthetasc y2 (reaching beyond tip of terminal segment), z1–z3 setae long; this segment medially with two unequal dorsal setae (length of short one c. 2/3 of that of long one) and four ventral setae (t1–t4). Terminal segment ( Fig. 20D) with two serrated claws (GM and Gm), long g-seta and an aesthetasc y3, length of the latter c. half of that of accompanying seta.

Md-palp ( Fig. 20E–G): first segment with two large setae, 1 slender, long seta and a long, smooth α- seta. Second segment dorsally with three unequal long apical setae, length of the shortest c. 1/4 of that of the longest; ventrally with a group of three hirsute setae, one shorter seta and the β- seta, the latter plumose, coneshaped and with pointed tip. Penultimate segment consisting of three groups of setae: dorsally with group of four unequal long subapical setae; laterally with an apical Ύ–seta and three further smooth apical setae, the former stout, hirsute, long (length c. 1.8 times of that of the terminal segment); ventrally with two (one long, one short, the latter c. half the length of the terminal segment) apical setae. Terminal segment ( Fig. 20G) bearing three claws and three setae.

Mx1 ( Fig. 21A) with two-segmented palp, three endites and a large branchial plate; basal segment of palp with a group of five unequal long apical setae and two (one long, one shorter, the latter not reaching tip of terminal segment) subapical setae, terminal segment elongated (length more than twice the width), with three claws and three setae. Two large bristles on third endite distally serrated. Sideways directed bristles on first endite unequal (one almost twice as long as other).

T1 ( Fig. 21B–C): protopodite with two long a-setae, a long b-seta, but without d-seta, distally with 14 (10 apical, four subapical) long, hirsute setae. Endopodite a weakly built palp with three unequal apical setae ( Fig. 21C).

T2 ( Fig. 21D) with slim d-setae, d1 almost twice as long as d2. Second segment with one long apical seta (length c. half of that of penultimate segment). Penultimate segment divided, proximal segment (a) bearing 1 long apical seta (reaching beyond tip of terminal segment), distal segment (b) with a pair of apical setae (one short, one spine-like). Terminal segment with two (one dorsally, one ventrally) short apical setae and a serrated claw.

T3 ( Fig. 21E–F) a cleaning limb. First segment with three long setae. Second segment with one long apical seta (more than half of the next segment). Third segment with medially one long seta (reaching beyond tip of the segment). Terminal segment with an apical pincer and one long reflexed subapical seta.

Caudal ramus ( Fig. 21H) slender, with ventral margin serrated, distal and proximal claws slender, long, serrated, length of distal claw c. half of that of ramus, length of proximal claw c. 2/3 of that of distal claw. Distal seta long (as long as proximal claw), proximal seta short (not reaching tip of ramus).

Caudal ramus attachment ( Fig. 21G) stout, with Triebel’s loop situated at middle of distal part of main branch, dorsal branch short, ventral branch well-developed.

Male unknown.

Remarks. The shape of the valves of this species are very reminiscent of Eucyprinotus rostratus (Sywula, 1966) (Eucypridinae) . However, the Triebel’s loop unequivocally places this species in the Cypricercinae , where it belongs to the genus Pseudostrandesia . In addition, the anterior pustules on the valves were for a long time considered to be characteristic of the genus Eucypris (also in Eucypridinae ). Meanwhile, however, such pustules (also often referred to as ‘ Porenwarzen’) have also been found in species of Heterocypris (Cyprinotinae) (Martens, unpubl.) so that this character can clearly be homeomorphic over various groups in the Cyprididae . Nevertheless, both congruencies support a close relationship amongst the three subfamilies.