Strandesia amnatcharoenensis, Savatenalinton, 2024

Savatenalinton, Sukonthip, 2024, Two new species of Strandesia Stuhlmann, 1888 (Crustacea: Ostracoda) from Thailand, with first record of a male S. martensi Savatenalinton, 2015, European Journal of Taxonomy 930, pp. 249-276 : 258-265

Strandesia amnatcharoenensis sp. nov.

urn:lsid:zoobank.org:act:FAE0F505-F607-49FC-AD84-30FA88385A32

Figs 5–8

Diagnosis

Cp medium size (ca 1090 μm), elongated in lateral view (L ca 1.8–2 × of H), LV slightly overlapping RV anteriorly, RV overlapping LV posteriorly, RV with posterior flange and external side with slightly compressed posterior end, A1 seven-segmented with large R, WO present, A2 with long natatory setae, aesthetasc Y slender, β seta on Md-palp large, two large bristles on third endite of Mx1 serrated, d seta on T1 present, T2 with large d1 and d2 setae (length of d2 seta more than half length of d1 seta), f and h3 setae long, CR robust, claw Ga large and long (length more than half length of ramus), claws Ga and Gp with tiny spine-like setules, ventral margin of ramus set with 5–6 groups of tiny spine-like setules, setules gradually smaller to posterior direction in each group, sa seta longer than claw Gp, sp seta slender with cilia-like tip, reaching slightly beyond tip of ramus, CR attachment stout with Triebel’s loop situated at middle of distal part of main branch.

Etymology

The species is named after Amnat Charoen Province, where the new species was discovered.

Type material

Holotype THAILAND – Amnat Charoen Province · ♀, soft parts dissected in glycerine on a sealed glass slide and valves stored dry in a micropalaeontological slide; Nong Sam Kha (swamp), Hua Taphan District ; 15°41.5′ N, 104°29.5′ E; 10 Feb. 2011; MSU-ZOC.376 .

Paratypes THAILAND – Amnat Charoen Province · 2 ♀♀, stored as the holotype; same collection data as for holotype; MSU-ZOC.378 , 380 • ♀, carapace stored dry in a micropalaeontological slide; same collection data as for holotype; MSU-ZOC.377 • 3 ♀♀, soft parts dissected in glycerine on a sealed glass slides and valves kept in ethanol; same collection data as for holotype; MSU-ZOC.379 , 381 to 382 .

Description

Female

MEASUREMENTS (in μm). Cp (n=2): L=1080–1107, H =592–615, W=535–560; LV (n =4): L=1057– 1080, H =560–585; RV (n =4): L=1080–1106, H=589– 614.

CP. (medium size) (ca 1090 μm). Elongated in lateral view ( Fig. 5B ) (L ca 1.85–2 × H), anterior margin widely rounded, posterior margin slightly narrowly rounded, LV slightly overlapping RV anteriorly, RV overlapping LV posteriorly, dorsal margin gradually arched, greatest height situated in front of mid-length, valve surface weakly reticulated and set with dispersed rimmed-pore setae and tiny tubercles at posterior half.

CP IN DORSAL VIEW ( Fig. 5A, D ). Subelliptical, with greatest W situated at mid-length and pointed anterior and posterior extremities, posterior margin of RV slightly more protruded than LV and external margin with slightly compressed posterior end.

LV IN INTERIOR VIEW ( Fig. 5E ). With groove along valve margin, anterior fused zone as wide as in posterior fused zone, dorsal margin slightly arched, greatest height situated at ca ⅓ of length; gently sloping down to anterior and posterior margins, the former widely rounded, the latter slightly less widely rounded, ventral margin slightly sinuated at mid-length; calcified inner lamella relatively wide anteriorly, without inner list, posteriorly narrower.

RV IN INTERIOR VIEW ( Fig. 5F ). With anterior marginal selvage and posterior flange, calcified inner lamella without inner list, anteriorly broader than posteriorly.

A1 ( Fig. 6A ). First segment with one thin dorso-subapical seta of intermediate length (reaching beyond tip of segment) and two long ventro-apical setae, WO present. Second segment slightly wider than long, with one markedly short dorso-apical seta (length ca ¼ of that of third segment) and a long R. Third segment bearing two (one dorso-apical and one ventro-apical) setae of intermediate length, both reaching mid-length of fifth segment. Fourth segment with two long dorsal setae and two (one short, one longer) ventral setae, short one reaching mid-length of next segment, longer one reaching mid-length of penultimate segment. Fifth segment dorsally with two long setae, ventrally with three (one long, one shorter and one very short) setae, shorter one reaching tip of terminal segment, shortest one reaching mid-length of next segment. Penultimate segment with four long setae. Terminal segment with three (two long, one short) apical setae and aesthetasc y a, shortest seta slightly longer than aesthetasc y a, aesthetasc y a long (ca 2.4 × terminal segment).

A2 ( Fig. 6B–C ). Protopodite with three proximal setae (two ventrally, one laterally), exopodite with three (one long, two short) setae, long one reaching beyond tip of first endopodal segment. First endopodal segment with five long natatory setae (not reaching tip of terminal claws) and one accompanying seta of intermediate length (almost reaching half way the penultimate segment), aesthetasc Y small (short and slender), insertion situated ca ⅓ of segment, ventro-apical seta long, reaching tip of penultimate segment. Penultimate segment undivided, distally with three serrated claws (G1–G3), aesthetasc y2 long (reaching beyond tip of terminal segment), z1–z3 setae long; this segment medially with two (one long, one shorter) dorsal setae (length of long one ca 2 × that of short one) and four ventral setae of unequal length (t1–t4). Terminal segment with two serrated claws (GM and Gm), g seta and aesthetasc y3, length of Gm ca ⅔ of that of GM, aesthetasc y3 remarkably short (length ca ⅓ of that of Gm and ca ½ of that of accompanying seta), length of g seta subequal to aesthetasc y3.

MD-COXA ( Fig. 6D ). Elongated, distally set with rows of teeth (large dorsally and smaller ventrally) and small setae, and with one dorso-subapical seta, latter short (not reaching base of teeth).

MD-PALP ( Fig. 7A–B ). First segment with two large setae (S1 and S2), one long, slender seta and long, smooth α seta with wide base and needle-like tip. Second segment dorsally with three unequal long apical setae, length of longest seta ca 3.8 × that of shortest seta; ventrally with group of three long hirsute setae, one shorter hirsute seta and the β seta, latter large, plumose, cone-shaped and with needle-like tip. Penultimate segment consisting of three groups of setae: dorsally with group of four unequal, long, subapical setae; laterally with apical γ seta and three apical setae, former stout, hirsute, long (length ca 1.8 × that of terminal segment); ventrally with two (one long, one short) apical setae. Terminal segment bearing three claws and two setae.

MX 1 ( Fig. 7C ). With two-segmented palp, three endites and large branchial plate; basal segment of palp with group of five long, unequal apical setae, one long subapical seta and one short subapical setae medially, latter reaching half way of terminal segment, terminal segment elongated, apically with four claws and one seta. Two large bristles on third endite serrated.

T1 ( Fig. 7D–F ). Protopodite with two short a setae, long b- and d setae, distally with 14 (10 apical, four subapical) hirsute setae of unequal length. Endopodite weakly built palp with three unequal apical setae, shortest one less than ⅓ of length of longest one.

T2 ( Fig. 8A –B ). With large d1 and d2 setae, length of d1 seta ca 1.7 × that of d2 seta. Second segment with e seta of intermediate length (reaching beyond mid-length of penultimate segment). Penultimate segment divided, proximal segment bearing long f seta (reaching far beyond tip of terminal segment), distal segment with long g seta (reaching far beyond tip of terminal segment). Terminal segment with two (one dorsally, one ventrally) apical h1 and h3 setae and serrated claw (h2), h3 seta long and subequal in length to h1 seta, length of claw h2 longer than that of penultimate segment.

T3 ( Fig. 8C ). Cleaning limb. First segment with long d1, d2, dp setae. Second segment with long apical e seta (ca ¾ of next segment). Third segment with medially short f seta (not reaching tip of segment). Terminal segment with apical pincer and three setae, one short h1 seta, one claw-like h2 seta and one reflexed subapical h3 seta, length of latter ca ½ of that of third segment.

CR ( Fig. 8D ). Robust, claw Ga large and long (length more than half length of ramus), claws Ga and Gp with tiny spine-like setules, length of claw Gp ca ⅔ of that of claw Ga. sa seta longer than claw Gp. sp seta slender with cilia-like tip, reaching slightly beyond tip of ramus. Ventral margin of ramus set with 5–6 groups of tiny spine-like setules, setules gradually smaller to posterior direction in each group.

CR ATTACHMENT ( Fig. 8E ). Stout with Triebel’s loop situated at middle of distal part of main branch, db and vb well-developed.

Male Unknown.

Type locality

A total of 7 female specimens were collected at the type locality on 10 Feb. 2011. Accompanying ostracod fauna: Bradleystrandesia weberi (Moniez, 1892) , Cypretta aculeata Savatenalinton, 2018 , C. triangulata Savatenalinton, 2018 , Dentocypria smithi Savatenalinton, 2017 , D. chantaranothaii Savatenalinton, 2017 , Pseudostrandesia striatoreticulata (Klie, 1932) , Strandesia kraepelini (G.W. Müller, 1906) , S. martensi Savatenalinton, 2015 .

Remarks

As the Cp in lateral view ( Fig 5B ) was slightly deformed appearing in a faintly compressed shape vertically, its height is thus not taken into account. Several individuals decalcified resulting in the deformation of valves after drying in the micropalaeontological slides, so separated valves of some specimens were kept in ethyl alcohol.

Figures

Fig. 5. Strandesia amnatcharoenensis sp. nov., ♀. A–D. Paratype (MSU-ZOC.377). A. Cp, dorsal view. B. Cp, right lateral view. C. valve surface of Cp, right lateral view. D. Cp, dorsal view. E–F. Paratype (MSU-ZOC.379). E. LV, internal view. F. RV, internal view (ditto). Scale bars: A–B, D–F =100 μm; C=10 μm. Arrows point to anterior side, arrowheads point to a small external compression on the RV posterior. Abbreviations: see Material and methods.

Fig. 6. Strandesia amnatcharoenensis sp. nov.,♀, holotype (MSU-ZOC.376). A. A1.B. A2.C. Terminal segment of A2. D. Md-coxa. Abbreviations: see Material and methods.

Fig. 7. Strandesia amnatcharoenensis sp. nov., ♀, holotype (MSU-ZOC.376). A. Md-palp. B. Terminal segment of Md-palp. C. Mx1. D. Terminal part of T1 protopodite. E. Endopodite of T1 (palp). F. T1. Abbreviations: see Material and methods.

Fig. 8. Strandesia amnatcharoenensis sp. nov., ♀, holotype (MSU-ZOC.376). A. T2. B. Knee segment of T2. C. T3. D. CR. E. CR attachment. Abbreviations: see Material and methods.