Cypretta aculeata, Savatenalinton, 2018

Savatenalinton, Sukonthip, 2018, Two new species of Cypretta Vávra, 1895 (Crustacea, Ostracoda) from Thailand and discussion of genus, Zootaxa 4532 (4), pp. 483-502 : 484-489

Cypretta aculeata n. sp.

( Figs 1–3 , 7 A–D)

2016 Cypretta sp. 1—Savatenalinton & Suttajit: 4, Table 2.

Holotype. Female, soft parts dissected in glycerine on a sealed glass slide, and valves stored dry in a micropalaeontological slide ( MSU-ZOC.235).

Paratypes. Three dissected females ( MSU-ZOC. 236–238) stored like the holotype, one undissected female carapaces ( MSU-ZOC. 239) stored dry in micropalaeontological slides and several females in 70% EtOH .

Type locality. Kwan Phayao (lake), Muang District, Phayao Province, collected on September 24 th, 2005, coordinates: 19° 09΄ 33˝ N and 99° 54΄ 36˝ E. Accompanying ostracod fauna: Bradleystrandesia weberi ( Moniez, 1892) , Cypridopsis sp., Dentocypria chantaranothaii Savatenalinton, 2017 , Dentocypria smithi Savatenalinton, 2017 , Stenocypris orientalis Victor & Fernando, 1981, Strandesia kraepelini (Müller, 1906) and Strandesia perakensis Victor & Fernando, 1981 .

Other localities. 30 localities (see appendix).

Etymology. The species name “aculeata” refers to the prickly valve surface, it is a distinctive feature of this new species.

Diagnosis. Carapace in lateral view subtriangular, anterior and posterior margins subequally rounded, dorsal margin strongly arched, greatest height situated at mid-length, RV overlapping LV anteriorly, ventrally, posteriorly. Septa well developed along anterior margins with c. 14–16 septa. Valve surface equipped with long setae, spinelike bristles and finely dispersed distinctive pits. Carapace in dorsal view subglobular, greatest width situated at mid-length. LV in internal view: anterior inner lamella with straight lines, inward edge of anterior valve slightly sinuated, posterior part with weak inner ridge, postero-ventral margin with c. 13 tubercles. RV in internal view: anterior inner lamella wide, with straight lines and 1 inner list, postero-ventral part with denticulated ridge (c. 15 denticles) and complementary sockets of tubercles. Length of A1 aesthetasc ya c. 6.5 times of that of terminal segment. Length of the shortest natatory seta nearly reaching tip of penultimate segment. Two large bristles on third endite of Mx1 slightly serrated distally (one obvious serrated, another one weak serrated). b- and c- setae on T1 absent. d1 and d2 on T2 long, thin, subequal in length. T3 with short e-seta (considerably less than half of segment) and long f-seta (reaching tip of segment). CR with Ga and Gp thin, very long, length of Ga c. 3/4 of that of ramus, length of Gp c. 2/3 of that of Ga; Sa very short, Sp long (c. 3/4 of Gp or half of Ga).

Measurements (in µm). Female, carapace, L = 523–560 (n = 5), H = 396–410 (n = 5), W = 416–435 (n = 5); LV, L = 513–550 (n = 8), H = 390–410 (n = 8); RV, L = 528–560 (n = 8), H = 405–420 (n = 8).

Description of female. Carapace in lateral view ( Fig. 1A ) subtriangular, anterior margin rounded, posterior margin narrower rounded, dorsal margin strongly arched, greatest height situated at mid-length, ventral margin slightly sinuated, RV overlapping LV anteriorly, ventrally, posteriorly; anterior of RV and LV with c. 1 4–16 septa; valve surface set with long setae, spine-like bristles and distinctive pits ( Fig. 1C ).

Carapace in dorsal view ( Fig. 1B ) subglobular, greatest width situated at mid-length, posterior extremity round, anterior extremity narrower rounded.

LV in internal view ( Fig. 1D , 7 A–B) with both valve margins subequally rounded, anterior inner lamella wide with straight lines, anterior inward margin slightly sinuated resulting from c. 5–7 weakly knob-like projections on inward edge, posterior extremity slightly pointed with blunt end at mid-height, posterior inner lamella with weak inner ridge, postero-ventral margin with c. 13 tubercles, ventral margin slightly sinuous at mid-length.

RV in internal view ( Fig. 1E , 7 C–D), anterior inner lamella large with straight lines and one submarginal inner list, postero-ventral part with denticulated ridge (c. 15 denticles) and complementary sockets of tubercles, ventral margin sinuous at mid-length.

A1 ( Fig. 2A ): seven-segmented, first segment with one long dorso-subapical seta (reaching half of next segment) and two long ventro-apical setae. Second segment slightly wider than long, with one short dorso-apical seta (reaching beyond tip of segment) and Rome organ. Third segment bearing two setae: one long dorso-apical (reaching beyond tip of penultimate segment) and one short ventro-apical setae (reaching tip of next segment). Fourth segment with two long dorsal setae and two short ventral setae (one reaching tip of next segment, another one reaching slightly beyond tip of penultimate segment). Fifth segment dorsally with two long setae, ventrally with two short setae, longer one reaching tip of terminal segment. Penultimate segment with four long apical setae. Terminal segment with three (two long, one shorter) apical setae and long aesthetasc ya, length of aesthetasc ya c. 6.5 times of that of terminal segment.

A2 ( Fig. 2B ): exopodite with three (one long, two short) setae, long one reaching beyond tip of first endopodal segment. First endopodal segment with five long (reaching far beyond tips of terminal claws) and one short natatory setae, length of the shortest seta almost reaching tip of penultimate segment, aesthetasc Y long, ventroapical seta long, extending beyond tip of terminal segment. Penultimate segment undivided, distally with three serrated claws (G1, G2, G3), aesthetasc y2 short (reaching tip of terminal segment), z1–z3 setae long; this segment medially with two subequally long dorsal setae, four ventral setae of unequal length (t1–t4). Terminal segment distally with two serrated claws (GM and Gm), length of Gm c. 3/4 of that of GM; and aesthetasc y3, length of aesthetasc y3 c. half of accompanying seta.

Md-palp ( Fig. 2 C–D): first segment with two large setae, one long and slender seta, and a long, smooth α-seta. Second segment dorsally with three unequal long apical setae; ventrally with group of three long hirsute setae, one short hirsute seta and a 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; ventrally with long, subapical seta (length c. three times of terminal segment). Terminal segment bearing three claws and two shorter setae.

Mx1 ( Fig. 3A ) with two-segmented palp, basal segment of palp dorsally with group of four long, unequal apical setae and one long subapical seta; ventrally with one long subapical seta (reaching slightly beyond tip of terminal segment). Terminal segment elongated (length c. 1.8 times of width), apically with three claws and two setae. Large bristles on third endite slightly serrated distally (one clearly serrated, another one weakly serrated). Sideways-directed bristles on first endite subequal.

T1 ( Fig. 3 B–C): protopodite with two unequally short a-setae, distally with c. 13 hirsute setae of unequal length (10 apical and three subapical setae), medially with d-seta. Endopodite weakly built palp with one very long, hirsute and two unequally short apical setae.

T2 ( Fig. 3D ) with long, thin d1 and d2 setae, both subequal in length. Second segment with long e-seta (length c. 3/4 of penultimate segment). Penultimate segment divided, proximal segment bearing very long f-seta (reaching half of h2 claw), distal segment with short g-seta. Terminal segment with two (one dorsally, one ventrally) short apical h1 and h3 setae (h3 spine-like seta) and very long, serrated claw (h2), h2 c. twice as long as penultimate segment.

T3 ( Fig. 3E ) a cleaning limb. First segment with long d1, d2, dp setae (d1 shortest seta). Second segment with short apical e-seta (much less than half of next segment). Third segment medially with long f-seta (reaching tip of segment). Terminal segment with an apical pincer and one short reflexed subapical seta, length of the latter c. 3/4 of third segment.

CR ( Fig. 3F ) thin, ventral margin smooth. Ga and Gp thin, very long and slightly serrated distally, length of Ga c. 3/4 of that of ramus, length of Gp c. 2/3 of that of Ga; Sa very short, Sp long (c. 3/4 of Gp or half of Ga).

Male unknown.

Ecology and distribution. Cypretta aculeata n. sp. is an uncommon species in Thailand, which was found in 31 localities (from a total of 293 surveyed localities) in 32 provinces of the Northern, Northeastern and Central parts of the country. It was found in many types of habitats, namely lakes, swamps, reservoirs, ponds, rivers, canals, springs and rice fields. Along the peripheral zones of sampled localities, there were several types of aquatic plants, namely floating plants (e.g., Eichhornia crassipes , Salvinia cucullata , Pistia stratiotes , Ipomoea aquatica ), submerged plants (e.g., Hydrilla verticillata , Ceratophyllum demersum , Utricularia aurea , Spirogyra sp.) and emerged plants (e.g., Nymphaea pubescens , Cyperus sp.). The new species occurs at a pH range of 6.28–9.30, a temperature range of 25.5–33.7° C and a dissolved oxygen range of 2.14–8.26 mg /l.

Figures

FIGURE 1 Cypretta aculeata n. sp. A. Carapace, left lateral view (MSU-ZOC.239). B. Carapace, dorsal view (ditto). C. RV, external view (MSU-ZOC.235). D. LV, internal view (ditto). E. RV, internal view (ditto). Scale bar: 200 µm for A–B, D–E; 140 µm for C.

FIGURE 2 Cypretta aculeata n. sp. (MSU-ZOC.235). A. A1, B. A2, C. Md-palp, D. Terminal segment of Md-palp, E. Mdcoxa. Scale bar: 100 µm for A–B, E, 50 µm for C–D.

FIGURE 3 Cypretta aculeata n. sp. (MSU-ZOC.235). A. Mx1, B. T1, C. Terminal part of T1 endopodite, D. T2, E. T3, F. CR, G. CR-attachment. Scale bar: 50 µm for A–C, 100 µm for D–G.

FIGURE 7 Cypretta aculeata n. sp. (A–D) (MSU-ZOC.235), Cypretta triangulata n. sp. (E-H) (MSU-ZOC.240). A. LV, internal view, posterior part (arrow indicates tubercles). B. LV, internal view, anterior part (arrow indicates sinuated inward margin). C. RV, internal view, anterior part (arrows indicate septa). D. RV, internal view, posterior part (arrows indicate denticulated inner list and complementary sockets). E. LV, internal view, posterior part. F. LV, internal view, anterior part (arrow indicates sinuated margin). G. RV, internal view, anterior part (arrow indicates sinuated inward margin). H. RV, internal view, posterior part (arrow indicates denticulated inner list).