Cyprettadopsis sutura, Savatenalinton, 2020

Savatenalinton, Sukonthip, 2020, A new cypridopsine genus (Crustacea, Ostracoda) from Thailand, European Journal of Taxonomy 631, pp. 1-16 : 4-11

Cyprettadopsis sutura gen. et sp. nov.

urn:lsid:zoobank.org:act:DE72C4CD-EC69-459D-A285-29DDB6A07C1C

Figs 1–5

Etymology

The specific epithet ‘ sutura ’ meaning ‘suture’ refers to the prominent appearance of tiny, needlepointlike pores along the anterior and ventral margins of both valves that look like a line of fabric suture.

Material examined

Holotype

THAILAND – Phayao Province · ♀ (soft parts dissected in glycerine on a sealed glass slide and valves stored dry in a micropalaeontological slide); Mae Jai District, Mae Puem Reservoir ; 19°21′27.0″ N, 99°52′06.4″ E; 24 Sep. 2005; MSU-ZOC.267.

Paratypes

THAILAND – Phayao Province · 1 ♀ (stored as the holotype); same collection data as for holotype; MSU-ZOC.268 · 2 ♀♀ (carapaces stored dry in micropalaeontological slides); same collection data as for holotype; MSU-ZOC.269 to 270. – Phitsanulok Province · 1 ♀ (stored as the holotype); Wat Bot District, roadside canal; 17°01′48.9″ N, 100°18′51.2″ E; 11 Nov. 2006; MSU-ZOC.271 · 1 ♀ (carapace stored dry in micropalaeontological slide); same collection data as for preceding; MSU-ZOC.272. – Ubon Ratchathani Province · 1 ♀ (stored as the holotype); Phibun Mangsahan District, Kaeng Saphue, stony river; 15°14′32.0″ N, 105°14′37.9″ E; 24 Oct. 2010; MSU-ZOC.273 · 19 ♀♀ (in 70% ethanol); same collection data as for preceding; MSU-ZOC.274.

Accompanying ostracod fauna

Type locality – Bradleystrandesia weberi (Moniez, 1892) , Bradleytriebella lineata (Victor & Fernando, 1981) , Chrissia ceylonica (Daday, 1898) , Cypretta aculeata Savatenalinton, 2018 , Dentocypria chantaranothaii Savatenalinton, 2017 , Pseudocypretta maculata Klie, 1932 , Pseudostrandesia striatoreticulata (Klie, 1932) , Strandesia kraepelini (Müller, 1906) .

Other localities – Phitsanulok Province · Wat Bot District, roadside canal; 11 Nov. 2006; Bradleystrandesia weberi , Chrissia sp., Cypretta aculeata , Dentocypria aequiloba Savatenalinton, 2017 , Pseudostrandesia mamarilorum (Victor & Fernando, 1981) , Stenocypris orientalis Victor & Fernando, 1981 , Strandesia kraepelini . – Ubon Ratchathani Province · Phibun Mangsahan District, Kaeng Saphue (stony river); 24 Oct. 2010; Chrissia sp., Pseudocypretta maculata , Pseudostrandesia calapanensis (Tressler, 1937) , P. gaetani Savatenalinton & Martens, 2010 , Strandesia kraepelini , S. sexpunctata Klie, 1932 , Thaicypridopsis longispinosa Savatenalinton, 2018 .

Diagnosis

Cp in lateral view subtriangular, with maximum height situated at mid-length, anterior and posterior ends subequally rounded. Cp in dorsal view subelliptical, with maximum width situated slightly behind midlength. LV obviously overlapping RV anteriorly and ventrally, RV slightly overlapping LV posteriorly. Complete marginal septa on posteroventral part of both valves, incomplete septa (or septa-like structure) on anterior part of both valves, tiny needlepoint-like pores present along anterior and ventral margins of both valves. LV with one anterior inner list, double posterior inner list, the latter not parallel to valve margin at posteroventral part. RV with large posterior selvage. Valve surface with shallow pits around mid-length of Cp and with sparse thin setae. A2 with long natatory setae, subquadrate terminal segment, claw G2 slender and strongly serrated apically; β-seta on Md palp very large, two large bristles on MX 1 third endite smooth, terminal segment of Mx1 palp cylindrical (ca 1.3 times as long as wide); b-, c- and d-setae on T1 absent; T2 penultimate segment not divided, d2 seta present in remarkably short length, d1 seta absent; T3 with distinctly separated terminal segment, markedly long h2 seta (ca ¾ of length of penultimate segment) and long h1 seta (length ca half that of h2 seta); CR reduced, with cylindrical base, laterally with short seta and flagellum-like distal claw.

Differential diagnosis

At first glance, Cyprettadopsis sutura gen. et sp. nov. resembles Cypridopsis gibba and Cypridopsis tumidula (see Sars 1910) because of the external morphology of its carapace, especially the shape. However, Cyprettadopsis sutura gen. et sp. nov. is apparently separated from them by the presence of marginal septa. In addition, other discriminating characters are also recognized in the new species, namely the tiny needlepoint-like pores along the anterior and ventral margins of both valves, the T2 undivided penultimate segment, the considerably short d2 seta on the T2, the distinctly separated terminal segment of the T3 and the remarkably large β-seta on the Md palp. A combination of these features is not found in any other cypridopsine species.

Measurements (in μm)

Cp (n =7): L = 399–416, H = 224–237, W = 227–240; LV (n =3): L = 399–416, H = 230–243; RV (n=3): L = 394–413, H = 227–241.

Description

Female

CP IN LATERAL VIEW ( Fig. 1A ). Subtriangular, anterior and posterior ends subequally rounded, dorsal margin evenly arched, maximum height situated at mid-length, LV obviously overlapping RV anteriorly and ventrally, RV slightly overlapping LV posteriorly, valve surface with shallow pits around mid-length of Cp and with sparse thin setae, tiny needlepoint-like pores present along anterior margins of both valves.

CP IN DORSAL VIEW ( Fig. 1B ). Subelliptical, with evenly curved lateral margins, maximum width situated slightly behind mid-length, posterior extremity round, anterior extremity more pointed.

CP IN VENTRAL VIEW ( Fig. 1 C–D). With tiny needlepoint-like pores along ventral borders of both valves, except for middle part; LV margin not straight (slightly curved at mid-length).

LV IN INTERNAL VIEW ( Fig. 1E ). With anterior and posterior valve margins subequally rounded, ventral margin slightly sinuous at mid-length, submarginal selvage anteriorly, anterior calcified inner lamella wide, with one inner list, posterior calcified inner lamella narrow, with double posterior inner list well developed but not parallel to valve margin at posteroventral part. Complete marginal septa on posteroventral part, incomplete septa on anterior part ( Fig. 2A ).

RV IN INTERNAL VIEW ( Fig. 1F ). With anterior and posterior valve margins subequally rounded, ventral margin sinuous at mid-length, submarginal selvage anteriorly, anterior calcified inner lamella wide, with incomplete inner list (only on mouth area), posterior calcified inner lamella narrow, with incomplete inner list (only on posteroventral part), posterior selvage moderate. Complete marginal septa on posteroventral part, incomplete septa on anterior part ( Fig. 2B ).

A1 ( Fig. 3A ). Seven-segmented, first segment with one short dorso-subapical seta (reaching tip of neXt segment) and two long ventro-apical setae. Second segment ca two times as wide as long, with one short dorso-apical seta (reaching ¼ of neXt segment) and small Rome organ. Third segment bearing two setae: one long dorso-apical (reaching beyond tip of penultimate segment) and one short ventro-apical setae (reaching half of next segment). Fourth segment with two long dorsal setae and two short ventral setae (both reaching tip of next segment). Fifth segment dorsally with two long setae, ventrally with two (one long, one short) setae, short one reaching half of terminal segment. Penultimate segment with four long apical setae and one short seta (reaching tip of terminal segment). Terminal segment with three (two long, one short) apical setae and long aesthetasc ya, length of aesthetasc ya ca equal to that of last five segments, length of short seta ca ¾ that of aesthetasc ya.

A2 ( Fig. 3B ). Basal segment with one long ventro-apical seta. Exopodite with three (one long, two short) setae, long one reaching slightly beyond half of penultimate segment. First endopodal segment with five very long setae (reaching far beyond tips of terminal claws) and one short natatory seta, length of shortest seta reaching half of penultimate segment, aesthetasc Y long, ventro-apical seta long, extending beyond tip of terminal segment. Penultimate segment undivided, distally with three large, serrated claws (G1–G3), G2 strongly serrated apically, serration appearing almost half of length, aesthetasc y2 very long (reaching mid-length of aesthetasc y3), z1–z3 setae long, Z1 slightly larger than other z setae, z2–z3 reaching tip of claws G1–G3; this segment medially with two subequally long dorsal setae, four ventral setae of unequal length (t1–t4), one t seta with claw-like appearance. Terminal segment subquadrate, distally with two serrated claws (GM and Gm), length of Gm ca ¾ that of GM; medially with very short g seta and ventral aesthetasc y3, length of aesthetasc y3 slightly greater than that of accompanying seta.

MD-PALP ( Fig. 4A ). First segment with two large setae (S1 and S2), one long and slender seta, and a smooth α-seta. Second segment dorsally with three unequal, long apical setae, shortest seta reaching tip of next segment; ventrally with group of three long hirsute setae (setules not drawn), one shorter hirsute seta (setules not drawn) and remarkably large, plumose, cone-shaped β-seta with pointed tip. Penultimate segment bearing three groups of setae: dorsally with group of four unequal, long, subapical setae; laterally with apical γ-seta and three further apical setae, the former slightly plumose (length ca 2.8 times that of terminal segment); ventrally with two subapical setae, one long (reaching ca ¾ of terminal claws), one short (ca half of terminal segment). Terminal segment bearing three large claws and three shorter setae, large claws ca three times as long as terminal segment.

MD-COXA ( Fig. 4B ). Elongated, distally with rows of teeth and small setae, and with one dorso-subapical seta situated close to palp.

MX 1 ( Fig. 4C ). With two-segmented palp, basal segment of palp dorsally with group of five long, unequal apical setae; ventrally with one long subapical seta (not reaching half of terminal segment), terminal segment elongated (ca two times as long as wide), apically with three claws and two setae. Third endite with two large, pointed-tip bristles (without spatula-shaped apex). Two sideways-directed bristles (one bristle drawn) on first endite long, subequal in length.

T1 ( Fig. 4 D–E). Protopodite with two a-setae, long one more than two times as long as short one; b-, c- and d-setae absent, distally with ca 10 hirsute apical setae of unequal length, no subapical setae. Endopodite ( Fig. 4C ) a weakly built palp with one very long, hirsute and two unequally shorter apical setae, length of shortest one less than ¼ that of long one.

T2 ( Fig. 5A ). With remarkably short d2 seta, d1 absent. Second segment with long e-seta (length ca ¾ that of penultimate segment). Penultimate segment undivided, medially with long f-seta (reaching beyond tip of terminal segment), distally with very short apical g-seta (not reaching tip of segment).

Terminal segment with two (one dorsal, one ventral) apical h1 and h3 setae (length of former ca ¼ that of claw, the latter short) and serrated claw (h2), length of h2 greater than that of last two segments.

T3 ( Fig. 5B ). First segment with short d1 and long d2 and dp setae, length of d1 seta ca half that of d2 and d3 setae. Second segment with short apical e-seta (not reaching ¼ of neXt segment). Third segment with short f-seta (not reaching tip of segment). Terminal segment completely separated from previous segment, bearing long seta (h1), claw-like seta (h2) and one refleXed subapical seta (h3), h1 reaching half of h2, h2 markedly long (ca ¾ length of third segment), h3 shorter than h2.

CR ( Fig. 5C ). Reduced, with cylindrical base, medially with short seta, distal claw flagellum-like, long seta (length ca 1.5 times that of ramus).

Male

Unknown.

Remarks

Cyprettadopsis sutura gen. et sp. nov. was encountered in environments with a temperature range of 20.3–33.7°C, a pH range of 6.33–9.97 and a DO range of 2.14–11.54 mg /l. It is considered to be an uncommon species due to its occurrence in only 60 (ca 19%) of the 313 surveyed localities. The new species was collected in both rainy and dry seasons from a wide range of habitats, namely swamps, (oXbow) lakes, reservoirs, ponds, rice fields, rivers, canals, weirs and streams. The fact that they can inhabit both running and standing waters, as well as permanent and temporary bodies of water, suggests a probably general habit of this species. However, its population size was remarkably small. Small populations of up to 5 specimens recovered per sample were recognized in 52 (87%) of the 60 localities from which the species was recorded. Seven localities harbored slightly larger populations, with specimen counts of 6–10, 15–20, 21–25 and 31–35, respectively, from 3, 2, 1 and 1 localities. Interestingly, one locality (Ban Don Pattana Reservoir, Mukdahan Province) yielded a very high abundance with more than 130 specimens. This sampling site was covered with very few aquatic plants and the substrate was sandy, with moderate organic detritus. The environmental conditions were measured with temperature, pH and DO being 25.5°C, 7.39 and 12 mg /l, respectively. As similar aspects of the habitat were also observed at other localities with low abundance, the apparent success of the species in this particular habitat is still unclear and remains to be elucidated by future investigation.

Figures

Fig. 1. Cyprettadopsis sutura gen. et sp. nov., ♀. A. Cp, right lateral view (MSU-ZOC.269). B. Cp, dorsal view (MSU-ZOC.270). C. Cp, ventral view (MSU-ZOC.269). D. Posterior part of Cp in ventral view (MSU-ZOC.272). E. LV, internal view (MSU-ZOC.268). F. RV, internal view (MSU-ZOC.268). Scale bar: A–C, E–F = 100 μm; D = 63 μm.

Fig. 2. Cyprettadopsis sutura gen. et sp. nov., ♀ (MSU-ZOC.268), drawn with transmitted light. A. LV, internal view. B. RV, internal view. Scale bars: 100 μm.

Fig. 3. Cyprettadopsis sutura gen. et sp. nov., ♀ (MSU-ZOC.267). A. A1. Aʹ. Rome organ of A1. B. A2. Scale bar: 50 μm.

Fig. 4. Cyprettadopsis sutura gen. et sp. nov., ♀. A–D. MSU-ZOC.267. A. Md palp. B. Md coxa. C. MX1, one sideways directed bristle on the first endite is drawn. D. T1. E. Terminal part of T1 endopodite (MSU-ZOC.268). Scale bars: A = 35 μm; B = 50 μm; C–E = 25 μm.

Fig. 5. Cyprettadopsis sutura gen. et sp. nov., ♀ (MSU-ZOC.267). A. T2. B. T3. C. CR. Scale bars: A = 50 μm; B = 40 μm; C = 25 μm.