Pseudostrandesia thailandensis, 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 : 44-47

Pseudostrandesia thailandensis sp. nov. ( Figs 28–31)

Holotype. A female, with soft parts dissected in glycerine in a sealed slide, and valves stored dry in a micropalaeontological slide (O.C.3135).

Paratypes. Three dissected females ( MSU-ZOC.041, MSU-ZOC.042, MSU-ZOC.045) stored as the holotype, three undissected females (O.C.3136, MSU-ZOC.043, MSU-ZOC.044) stored dry in micropalaeontological slides after use for SEM and several females in 70% EtOH .

Repository. 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. Nalao natural spring, Konsarn district, Chaiyaphum Province, collected on 28 September 2005 (TH054) and 9 October 2007 (TH151), coordinates: 16° 35´22˝ N and 101° 53´49.8˝ E. Accompanying ostracod fauna: Bradleystrandesia weberi ( Moniez, 1892) , Bradleytriebella lineata (Victor & Fernando, 1981) , Chrissia sp. , Cypretta sp.1 , Cypretta sp.2 , Cypretta sp.3 , Cypridopsis vidua (Müller, 1776) , Cypris subglobosa Sowerby, 1840 , Physocypria sp. , Pseudocypretta maculata Klie, 1932 , Pseudostrandesia mamarilorum (Victor & Fernando, 1981) , Strandesia hornei sp. nov., S.kraepelini ( Müller, 1906) , Stenocypris sp., Thaicythere srisumonae Savatenalinton, Borgonie & Martens, 2008 .

Other localities. 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. gaetani sp. nov., P. mamarilorum (Victor & Fernando, 1981) , P. phetchabunensis sp. nov., Sarscypridopsis sp. , Strandesia kraepelini ( Müller, 1906) .

Etymology. The new species is named after Thailand from where the species is described.

Diagnosis. Carapace in lateral view elongated (length 1.7 times width), anterior margin broadly rounded, posterior margin bluntly pointed, dorsal margin arched, greatest height situated at mid-length; valve surface weakly reticulated and set with dispersed setae; carapace in dorsal view subelliptical, with LV largely overlapping RV anteriorly and posteriorly, greatest width situated at mid-length; LV with internal groove along valve margin, calcified inner lamella wide anteriorly, set with one inner list; RV with marginal selvage; Wouters organ small, Rome organ long, aesthetasc ya on A1 shorter than short apical seta; aesthetasc Y on A2 slim; two large bristles on third endite of Mx1 distally serrated; d seta on T1 absent; length of distal claw of caudal ramus less than half of that of ramus, distal seta long, proximal seta remarkably long; 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. Pseudostrandesia thailandensis sp. nov. has P. mamarilorum (Victor & Fernando, 1981) as its closest congener. It can be distinguished by the large L/R overlap at both anterior and posterior ends (large anteriorly, slightly posteriorly in P. mamarilorum ), the ovate carapace in frontal view (rounded in P. mamarilorum ) and the long proximal seta of the caudal ramus (shorter in P.mamarilorum ).

Measurements (in µ m). LV (n=3), L=1250–1280, H=705–718; RV (n=3), L=1190–1230, H=702–718; Carapace (n=2), L=1210–1240, W=647–670.

Ecology. Pseudostrandesia thailandensis sp. nov. has to date been recorded from two habitat types: a natural spring and a swamp. The ranges of pH and temperature of waters in which this new species was found are 6.7–7.0 and 26.7–27.6° C, respectively.

Description of female. Carapace in lateral view ( Fig. 28A) elongated (length 1.7 times width), anterior margin broadly rounded, posterior margin bluntly pointed, dorsal margin arched, greatest height situated at mid-length, ventral margin almost straight; valve surface weakly reticulated and set with dispersed setae ( Fig. 28E–F).

Carapace in dorsal view ( Fig. 28C) subelliptical, with unequal anterior and posterior extremities, LV considerably longer than RV anteriorly and posteriorly, LV overlapping RV, greatest width situated at mid-length.

Carapace in ventral view ( Fig. 28D) LV overlapping RV, ventral margin of LV somewhat straight.

Carapace in posterior view ( Fig. 28B) ovate, with symmetrical position of both valves.

LV in interior view ( Fig. 29A, C–D, G) with groove along valve margin, dorsal margin arched, greatest height situated at c. mid-length, sloping down to anterior and posterior margins, the latter bluntly pointed; ventral margin slightly sinuous in front of mid-length; inner lamella calcified broadly anteriorly, with one inner list, narrower posteriorly.

RV in interior view ( Fig. 29B, E–F) with marginal selvage; ventral margin slightly sinuous in front of mid-length; calcified inner lamella broad anteriorly, without inner list, narrower posteriorly.

A1 ( Fig. 30A): first segment with long dorso-subapical seta (reaching tip of segment), two long, unequal ventro-apical setae and a small proximal Wouters organ. Second segment slightly wider than long, with one short dorso-apical seta and a long Rome organ. Third segment bearing two (one dorso-, one ventro-) apical setae, the former shorter (reaching tip of fourth segment), the latter long (reaching halfway fifth segment). Fourth segment with two long dorsal setae, 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, short one reaching beyond tip of the terminal 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 short apical seta.

A2 ( Fig. 30B–C): exopodite with three (one long, two short) setae, length of long one c. half of that of first endopodal segment. First endopodal segment with natatory setae long, length of shortest seta c. 1/4 of that of the penultimate segment, aesthetasc Y slim, ventro-apical seta long (reaching beyond tip of terminal segment). Penultimate segment undivided, distally with three serrated claws (length c. 1.2 times of that of penultimate segment) and with long aesthetasc y2 (c. 3/4 of length of terminal segment), z1–z3 setae long; this segment medially with two unequal dorsal setae (one almost twice as long as other), and four ventral setae (t1–t4). Terminal segment ( Fig. 30C) 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. 30D–F): first segment with two large setae, one slender, long seta and a long, smooth α- seta. Second segment dorsally with three long, unequal apical setae, length of shortest c. 1/3 of that of longest; ventrally with a group of three hirsute setae, one shorter seta and the β- seta, the latter plumose, cone-shaped and with pointed tip. Penultimate segment bearing three groups of setae: dorsally with a group of four long, but unequal subapical setae; laterally with an apical Ύ–seta and three further smooth apical setae, the former stout, hirsute, long (length c. 3 times that of terminal segment); ventrally with two (one long, one short, the latter c. 1/3 of length of terminal segment) apical setae. Terminal segment ( Fig. 30E) bearing three claws and three setae.

Mx1 ( Fig. 31A) 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 reaching tip of terminal segment) subapical setae, terminal segment elongated (length c. 3 times width), with three claws and three setae. Two large bristles on third endite distally serrated. Sideways directed bristles on first endite unequal, length of short one c. 3/4 of that of long one.

T1 ( Fig. 30H): protopodite with two short 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.

T2 ( Fig. 31B) with d1 larger and longer than d2 (d1 c. 1.4 times the length of d2). Second segment with one long apical seta (reaching tip of penultimate segment). Penultimate segment divided, proximal segment (a) bearing one 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 dorsal, one ventral) short apical setae and a serrated claw.

T3 ( Fig. 31C) a cleaning limb. First segment with three long setae. Second segment with one long apical seta (slightly more than half the length of next segment). Third segment with medially one long seta (reaching tip of segment). Terminal segment with an apical pincer and one long reflexed subapical seta.

Caudal ramus ( Fig. 31D) stout, with ventral margin serrated, distal and proximal claws long, serrated, length of distal claw less than half of that of ramus, proximal claw c. 2/3 of length of distal claw. Distal seta c. 7/8 of length of distal claw, proximal seta long (reaching far beyond end of ramus).

Caudal ramus attachment ( Fig. 31D) stout, with Triebel’s loop situated at middle of distal part of main branch, dorsal and ventral branches well-developed.

Male unknown.