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 : 12-15

Strandesia sanoamuangae sp. nov. ( Figs 5–8)

Holotype. Female, soft parts dissected in glycerine in a sealed slide, valves stored dry in a micropalaeontological slide (O.C.3127).

Paratypes. One dissected female ( MSU. ZOC.089) stored as the holotype, three undissected females (O.C.3128, MSU. ZOC.033, MSU. ZOC.034) stored dry in micropalaeontological slides 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 (Brussels, Belgium). One dissected, two dried undissected 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 15 November 2006 (TH135) and 9 October 2007 (TH151), coordinates: 16° 35´22˝ N and 101° 53´49.8˝ E. Accompanying ostracod fauna: Alicenula serricaudata (Klie, 1935) , Bradleystrandesia weberi ( Moniez, 1892) , Bradleytriebella lineata (Victor & Fernando, 1981) , Candona sp. , 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) , P. thailandensis sp. nov., Strandesia hornei sp. nov., S. kraepelini ( Müller, 1906) , Stenocypris sp., Thaicythere srisumonae Savatenalinton, Borgonie & Martens, 2008 , Vestalenula molopoensis (Martens & Rossetti, 1997) .

Etymology. The new species is named after Prof. Dr. La-orsi Sanoamuang (Khon Kaen University, Khon Kaen, Thailand), in recognition of her impressive contribution to aquatic sciences and taxonomy in Thailand.

Diagnosis. Carapace in lateral view subovate, with greatest height situated at c. 1/3 of length; valve surface set with tiny tubercles and rim-pore setae; LV overlapping RV anteriorly, ventrally and posteriorly; carapace in dorsal view subelliptical, with greatest width situated at mid-length; LV with internal groove along valve margin; inner lamella calcified, without inner list; A1 with long Rome organ, small Wouters organ, aesthetasc ya slightly longer than the short apical seta; aesthetasc Y on A2 long; two large bristles on third endite of Mx1 serrated; d seta on T1 present; length of distal claw of caudal ramus c. half of that of ramus; caudal ramus attachment stout, with Triebel’s loop situated at middle of distal part of main branch, dorsal branch short, ventral branch well-developed.

Differential diagnosis. Strandesia sanoamuangae sp. nov. strongly resembles Strandesia perakensis Victor & Fernando, 1981 and S. kraepelini (G.W. Müller, 1906) in the shape of the valves. It can be distinguished from the former by the structure of the valves (larger posterior overlap in right-lateral view and presence of a short anterior inner list in S. perakensis ) and especially of the valve surface, which is set with tiny tubercles and long setae in S. sanoamuangae sp. nov., and with pits, long setae and spines in S. perakensis . In addition, there are rimmed pores in S. sanoamuangae sp. nov., but not in S. perakensis . The new species also differs from S. perakensis in the presence of a longer Rome organ, a shorter aesthetasc ya and a slimmer caudal ramus attachment. Strandesia sanoamuangae sp. nov. can be distinguished from S. kraepelini by the larger overlap in right lateral view, the ornamentation of valve surface, which is set with tiny tubercles and long setae in S. sanoamuangae sp. nov., and with pits and setae in S. kraepelini , the presence of the dorsal subapical seta on the first segment of the A1, the long dorso-apical seta on the second segment of the A1, the length of the short apical seta on A1-terminal segment (considerably longer than aesthetasc ya in S. kraepelini ), the length of shortest natatory seta (considerably longer than that of S. kraepelini ) and a slimmer caudal ramus attachment.

Measurements (in µ m). Female: LV (n=1), L=802, H=461; RV (n=1), L=780, H=460; Carapace (n=2), L=802–815, W=428–430.

Ecology. The new species is only known from its type locality, namely Nalao natural spring. It occurs at a pH over 7.0 and a temperature range of 26.7–27.0° C.

Description of female. Carapace in lateral view ( Fig. 5A) subovate, anterior margin widely rounded, posterior margin more narrowly rounded, dorsal margin arched, greatest height situated at c. 1/3 of length, ventral margin slightly sinuous at c. mid-length; valve surface set with tiny tubercles and setae, the latter in rimmed pores ( Fig. 5D–E).

Carapace in dorsal view ( Fig. 5B) subelliptical, with greatest width situated at mid-length, sloping down to bluntly pointed anterior and posterior extremities; LV overlapping RV, larger anteriorly; dorsal margin anteriorly slightly curved outwardly.

Carapace in ventral view ( Fig. 5C) LV overlapping RV, ventral margin of LV protruding slightly at c. midlength.

LV in interior view ( Fig. 6A, C–D) with groove along valve margin, dorsal margin curved, greatest height situated at c. 1/3 of length, sloping down to anterior and posterior margins, the former widely rounded, the latter more narrowly rounded; ventral margin almost straight; inner lamella calcified, anteriorly wide, without inner list, posteriorly narrower.

RV in interior view ( Fig. 6B, E–F) without selvage, inner lamella without inner list, anteriorly broader than posteriorly.

A1 ( Fig. 7A): first segment with a long dorsal, subapical seta (reaching slightly beyond the middle of the next segment), with two long ventro-apical setae and a small proximal Wouters organ. Second segment slightly wider than long, with one long dorso-apical seta and a long Rome organ ( Fig. 7B), the former reaching beyond middle of third segment. Third segment bearing two long (one dorso-, one ventro-) apical setae (reaching beyond distal end of fifth segment). Fourth segment with two long dorsal setae and two shorter ventral setae (the longer one reaching tip of terminal segment, the shortest reaching distal end of next segment). Fifth segment dorsally with two long setae, ventrally with two (one long, one short) setae, the short one reaching middle of terminal segment. Penultimate segment with five (four long, one short) setae, length of short one c. 2/3 of that of terminal segment. Terminal segment with three (two long, one short) apical setae and an aesthetasc ya, the latter slightly longer than the short apical seta.

A2 ( Fig. 7C): exopodite with three (one long, two short) setae, the long one reaching beyond tip of first endopodal segment. First endopodal segment with natatory setae long, length of shortest seta slightly more than half of that of penultimate segment, aesthetasc Y long, ventro-apical seta long (reaching beyond tip of terminal segment). Penultimate segment undivided, distally with three serrated claws (length c. 1.5 times penultimate segment) and with long aesthetasc y2 (reaching beyond tip of terminal segment), z1–z3 setae long; this segment medially with two (one long, one shorter) dorsal setae (length of short one c. 3/4 of that of long one) and four ventral setae (t1–t4). Terminal segment with two serrated claws (GM and Gm), long g-seta and an aesthetasc y3, length of the latter c. 2/3 of that of accompanying seta.

Md-palp ( Fig. 7E–G): first segment with two large setae, one slender, long seta and a long, smooth α- seta, the latter basally widened. Second segment dorsally with three unequal long apical setae, length of the shortest c. 1/3 of that of the 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 consisting of 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 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. 7F) bearing three claws and three setae.

Mx1 ( Fig. 8A) with a two-segmented palp, three endites and a large branchial plate; basal segment of palp with a group of five long, but unequal apical setae and two (one long, one shorter, the latter reaching tip of terminal segment) subapical setae, terminal segment elongated, with three claws and tree setae. Two large bristles on third endite distally serrated. Sideways directed bristles on first endite unequal, length of short one c. 2/ 3 of that of long one.

T1 ( Fig. 8B–D): protopodite with two long a-setae, a long b and a d-setae, distally with 14 (10 apical, four subapical) long, hirsute setae. Endopodite a weakly built palp with three unequal apical setae, these palps asymmetrical, one palp with, the other without a lateral seta ( Fig. 8C–D).

T2 ( Fig. 8E) with d-setae slim, length of d2 less than half of that of d1. Second segment with 1 long apical seta (length c. 2/3 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) apical setae and a serrated claw.

T3 ( Fig. 8F–G) a cleaning limb. First segment with three long setae. Second segment with one long apical seta (length slightly more than half of 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, length of the latter c. 2/3 of that of third segment.

Caudal ramus ( Fig. 8I) stout, with ventral margin slightly serrated, distal and proximal claws 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 (slightly longer than half of that of proximal claw), proximal seta long (reaching tip of ramus).

Caudal ramus attachment ( Fig. 8H) stout, with Triebel’s loop at middle of distal part of main branch, dorsal branch short, ventral branch well-developed.

Male unknown.

Remarks. The new species is thus far only known from its type locality.