Dentocypria mesquitai, Savatenalinton, Sukonthip, 2017

Savatenalinton, Sukonthip, 2017, A new genus and four new species of subfamily Cyclocypridinae (Crustacea, Ostracoda) from Thailand, Zootaxa 4243 (2), pp. 329-365 : 331-339

Dentocypria mesquitai n. gen. n. sp.

( Figs 1–6 )

Holotype. Male, soft parts dissected in glycerine on a sealed slide, valves stored dry in a micropalaeontological slide (MSU-ZOC.141).

Allotype. Female, stored like the holotype (MSU-ZOC.142).

Paratypes. Two dissected males (MSU-ZOC.143–145) stored like the holotype, three undissected males (MSU-ZOC.146–147) stored dry in micropalaeontological slides, two dissected females (MSU-ZOC.148–151) stored like the holotype, three undissected females (MSU-ZOC.152–153) stored dry in a micropalaeontological slide and c. 20 males and 30 females in 70% ethanol.

Repository. All specimens are deposited in the MSU-ZOC.

Type locality. Bueng Khong Lhong (swamp), Bueng Kan Province. Material collected on 30 Jan. 2011, coordinates: 17° 57΄ 35˝ N and 104° 02΄ 06˝ E. Accompanying ostracod fauna: Alicenula sp., Cypridopsis sp., Fabaeformiscandona subacuta ( Yang, 1982; in Hou et al., 1982), Limnocythere sp., Metacypris srisumonae (Savatenalinton et al., 2008) , Dentocypria smithi n. gen. n. sp., Pseudostrandesia striatoreticulata ( Klie, 1932) , Strandesia kraepelini ( G.W. Müller, 1906) , Strandesia martensi Savatenalinton, 2015 .

Other localities. 1) Kud Thing (swamp), Bueng Kan Province. Material collected on 30 Jan. 2011, coordinates: 18° 20΄ 36˝ N and 103° 39΄ 52˝ E. Accompanying ostracod fauna: Cypretta sp., Metacypris srisumonae (Savatenalinton et al., 2008) , Dentocypria smithi n. gen. n. sp., Strandesia martensi Savatenalinton, 2015 . 2) Nong Kon (swamp) , Nong Khai Province . Material collected on 30 Jan. 2011, coordinates: 18° 14΄ 44˝ N and 103° 11΄ 42˝ E. Accompanying ostracod fauna: Bradleystrandesia weberi ( Moniez, 1892) , Limnocythere sp., Physocypria sp., Pseudocypretta maculata Klie, 1932 , Pseudostrandesia gaetani Savatenalinton & Martens, 2010 , Pseudostrandesia cf. striatoreticulata , Strandesia kraepelini ( G.W. Müller, 1906) , Strandesia martensi Savatenalinton, 2015 . 3) A swamp in Bueng Kan District , Bueng Kan Province . Material collected on 30 Jan. 2011, coordinates: 18° 22΄ 16˝ N and 103° 37΄ 51˝ E. Accompanying ostracod fauna: Bradleystrandesia weberi ( Moniez, 1892) , Chrissia sp., Limnocythere sp., Physocypria sp., Pseudocypretta maculata Klie, 1932 , Stenocypris sp., Strandesia kraepelini ( G.W. Müller, 1906) , Strandesia martensi Savatenalinton, 2015 . 4) Nong Gom Goa (swamp) , Nong Khai Province. Material collected on 31 Jan. 2011, coordinates: 17° 49΄ 51˝ N and 102° 43΄ 38˝ E. Accompanying ostracod fauna: Hemicypris mizunoi Okubo, 1990 , Physocypria sp., Pseudocypretta maculata Klie, 1932 , Stenocypris sp.

Etymology. The new species is named after Prof. Dr. Francesc Mesquita-Joanes (University of Valencia, Spain) in recognition of his significant contributions to the knowledge on ostracods, especially with regard to ecology and for his friendship and assistance during my research stay in Valencia.

Diagnosis. Carapace in lateral view ovate, RV with large dorsal hump with straight dorsal margin (nearly parallel to ventral margin), valve surface reticulated with very long setae, CpD subelliptical, CpC subovate with very oblique valves. Male A2 with t2 and t3 setae transformed and markedly long. CR: Sa short (less than half of Ga), Sp very long (reaching mid-length of Ga). Right prehensile palp of male T1 without large distal protrusion on first segment, left prehensile palp with one very long apical spine. Hemipenis with a-lobe slightly longer than blobe, a-lobe elongated with pointed, protruding process dorsally.

Differential diagnosis. Dentocypria mesquitai n. gen. n. sp. is characterized by the large dorsal hump on the RV. It cannot be confused with any other Dentocypris species. Additionally, the valve ornamentation and chaetotaxy of the limbs are easily recognized, such as the reticulation of the valve surface with very long setae, the transformed and very markedly long t2 and t3 setae of male A2, the absence of a distal protrusion on the first segment of the right prehensile palp and the presence of a pointed projection on the dorsal margin of the hemipenis a-lobe.

Measurements (mean, in µm). Female, LV (n = 2), L = 490.2, H = 356.1; RV (n = 2), L = 469.5, H = 361.0; Carapace (n = 3), L = 492.7, H = 390.3, W = 243.9. Male, LV (n = 2), L = 458.5, H = 307.3; RV (n = 2), L = 439, H = 317; Carapace (n = 2), L = 450.0, H = 341.5, W = 204.9.

Description of female. Carapace in lateral view ( Fig. 1 A–B) ovate, anterior and posterior margins rounded, LV overlapping RV anteriorly, ventrally and posteriorly, dorsal margin arched, greatest high situated at mid-length, valve surface reticulated with very long setules ( Fig. 1 E).

CpD ( Fig. 1 C) subelliptical, with greatest width situated at mid-length.

CpC ( Fig. 1 D) subovate, strongly oblique, with large dorsal hump on RV.

LVi ( Fig. 2 A, D–E) with selvage slightly inwardly displaced along anterior margin, internal tooth on anteroventral part and tubercle-sockets anteriorly and posteriorly, calcified inner lamella anteriorly wider than posteriorly, with one inner list anteriorly.

RVi ( Fig. 2 B–C, F–G) with submarginal selvage anteriorly, dorsal hump large with straight dorsal margin (nearly parallel to ventral margin), complementary pit of internal tooth on antero-ventral part, valve margin tuberculated anteriorly and posteriorly, posterior tubercles more prominent than anterior ones, calcified inner lamella wide anteriorly and posteriorly, with one inner list

A1 ( Fig. 4 A): first segment with small proximal Wouters organ, one long dorso-subapical seta (reaching beyond tip of next segment) and two long ventro-apical setae. Second segment slightly wider than long, with one long dorso-apical seta (reaching beyond half of next segment) and small Rome organ. Third segment bearing two setae: one long dorso-apical (reaching beyond tip of penultimate segment) and one shorter ventro-apical setae (reaching beyond tip of next segment). Fourth segment with two long dorsal setae and two subequal ventral setae (short one reaching half of fifth segment, long one reaching beyond tip of fifth 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. Terminal segment with three (two long, one short) apical setae and aesthetasc y a, length of the latter c. 3/4 of that of short apical seta.

A2 ( Fig. 4 B): exopodite with three (one long, two short) setae, long one reaching beyond tip of first endopodal segment. First endopodal segment with five long (reaching tip of terminal claws) and one short natatory setae, length of the shortest seta less than half of penultimate segment, aesthetasc Y long, ventro-apical seta long, extending far beyond tip of terminal segment. Penultimate segment undivided, distally with three serrated claws (G1, G2, G3), G2 shorter (length of G2 c. 2/3 of that of G1), aesthetasc y2 very long (reaching beyond tip of terminal segment), z1 seta short, z2–z3 setae long; this segment medially with two subequally long dorsal setae, four ventral setae of unequal length (t1–t4) and aesthetasc y1, the latter short (not reaching tip of segment). Terminal segment distally with two serrated claws (GM and Gm), length of Gm c. 4/5 of that of GM; medially with ventral aesthetasc y3, length of aesthetasc y3 c. half of that of accompanying seta.

Md-palp ( Fig. 4 C): first segment with two large setae: one long and slender seta, and a short, smooth α-seta. Second segment dorsally with two unequal long apical setae; ventrally with group of three long hirsute setae, one shorter hirsute seta and the small, plumose, cone-shaped β-seta with pointed 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 further smooth apical setae, the former thin and long (length c. 3-4 of that of terminal segment); ventrally with two subapical setae, one very long (reaching beyond tip of terminal segment), one short (reaching tip of segment). Terminal segment very elongated (length c. 4 times of width) bearing three claws and one long seta.

Mx 1 ( Fig. 5 A) with two-segmented palp, three endites and large branchial plate; basal segment of palp dorsally with group of three long, unequal apical setae, one stout, plumose apical seta and two (one long, one shorter), subapical setae, the latter not reaching tip of terminal segment; ventrally with one stout, plumose subapical seta. Terminal segment short (width and length subequal), apically with three claws and three setae. Sideways-directed bristles on first endite unequally long, length of long one c. 2.5 times of that of short one.

T1 ( Fig. 5 B): protopodite with two subequally short a-setae, long b- and d-setae and additional long and stout seta, distally with c. 16 hirsute apical setae of unequal length. Endopodite weakly built palp with three unequal apical setae.

T2 ( Fig. 5 C) without d1 and d2 setae. Second segment with markedly long e-seta (reaching beyond tip of terminal segment). Penultimate segment divided, proximal segment bearing short f-seta (c. half of next distal segment), distal segment with pair of apical setae (long g-seta, one spine-like). Terminal segment with two (one dorsally, one ventrally) apical h1 and h3 setae (the latter spine-like) and serrated claw (h2), length of h2 longer than that of penultimate segment.

T3 ( Fig. 5 D): first segment with long d1, d2, dp setae, d1 and d2 setae subequal in length. Second segment with long apical e-seta (reaching half of next segment). Third segment with medially long f-seta (reaching tip of segment), g-seta short. Terminal segment short, with three setae, two short h1 and h2 setae (subequal in length with h2 slightly longer), and one reflexed subapical h3 seta, length of the latter equal of that of T3.

CR ( Fig. 5 E) well-developed, robust, ventrally with two parallel rows of setules, Ga and Gp large, serrated, length of Ga c. half of that of ramus, length of Gp c. 4/5 that of Ga. Sa short (less than half of Ga), Sp markedly long (reaching mid-length of Ga).

CR attachment ( Fig. 5 F) thin, with two proximal branches and distal branches.

Description of male. Carapace and valves ( Fig. 1 F–G, 3) as in female, but somewhat smaller. All limbs as in female, except for last two segments of A2 ( Fig. 6 A) and T1 ( Fig. 6 B–C).

A2 with divided penultimate segment and t2 and t3 setae transformed and markedly long (reaching far beyond tip of terminal segment). Setae z1 and z2 of penultimate segment transformed into claws; claw G1 reduced, appearing smaller and shorter than that of female; claw G3 reduced to seta (reaching slightly beyond tip of terminal segment); Gm on terminal segment of A2 reduced (length c. 2/3 of that of GM).

T1 with asymmetrical prehensile palps (endopodites). Right prehensile palp ( Fig. 6 B) with first segment bearing two short apical spines, distal margin with small, subtriangular protrusion; second segment large, subtriangular. Left prehensile palp ( Fig. 6 C) elongated with first segment bearing one very long apical spine; second segment narrow, curved and pointed.

Hemipenis ( Fig. 6 D): a-lobe elongated with a small pointed projection dorsally, b-lobe subtriangular, with pointed and slightly dorsally curved end, b-lobe slightly shorter than a-lobe.

Zenker organ ( Fig. 6 E) elongated, length c. 3 times width, set with seven chitinous spiny whorls.

Remarks. Apart from the internal tooth of LV, the other characteristics of Dentocypria mesquitai n. gen. n. sp. are the prominently reticulated valve ornamentation with very long setae, the strongly oblique carapace in caudal view and the obvious dorsal hump on the RV. Dentocypria mesquitai n. gen. n. sp. belongs to the species group with a dorsal hump, such as Physocypria pustulosa ( Sharpe, 1897) , Physocypria inflata Furtos, 1933 , Physocypria gibbera ( Furtos, 1936) and Physocypria kerkyrensis Klie, 1936 . The new species differs from P. pustulosa by the presence of a dorsal hump on the RV (it is on the LV in P. pustulosa ) and from P. inflata by the morphology of the dorsal hump, namely a smaller size and no sinuation at the mid length of dorsal hump. While the margin of the dorsal hump is rather flat in Dentocypria mesquitai n. gen. n. sp., it is arched in P. gibbera . Dentocypria mesquitai n. gen. n. sp. has a selvage, which is slightly inwardly displaced along the anterior margin of the LV, whereas such feature is absent in P. kerkyrensis . Additionally, the tooth occurring at the antero-ventral part of the internal LV is absent in all four closest Physocypria species.

Dentocypria mesquitai n. gen. n. sp. has so far been recognized only from five swamps in Bueng Kan and Nong Khai, provinces, which are situated along the Khong River. The peripheral zones of all five swamps are densely covered by macrophytes and algae.

Figures

FIGURE 1. Dentocypria mesquitai n. gen. n. sp., female (A – E), male (F – G). A. CpR (MSU. ZOC. 150). B. CpL (MSU. ZOC. 151). C. CpD (MSU. ZOC. 152). D. CpC (MSU. ZOC. 152). E. ornamentation of valve surface (MSU. ZOC. 150). F. CpR (MSU. ZOC. 145). G. CpD (MSU. ZOC. 145). Scale bars: A – D, F – G = 100 µm; E = 10 µm.

FIGURE 2. Dentocypria mesquitai n. gen. n. sp., female (MSU. ZOC. 149). A. LVi. B. RVi. C. muscle scars. D. posterior part of LVi. E. anterior part of LVi. F. anterior part of RVi. G. posterior part of RVi. Scale bars: A – B = 100 µm; C – G = 20 µm. Arrows point to internal tooth (A, E) and complementary pit (B, F).

FIGURE 3. Dentocypria mesquitai n. gen. n. sp., male (MSU. ZOC. 144). A. LVi. B. RVi. C. posterior part of LVi. D. anterior part of LVi. E. anterior part of RVi. F. posterior part of RVi. Scale bars: A – B = 100 µm; C – F = 20 µm. Arrow points to internal tooth (A).

FIGURE 4. Dentocypria mesquitai n. gen. n. sp., female (MSU. ZOC. 142). A. A 1. B. A 2. C. Md-palp. D. Md-coxa. Scale bar: A – B = 50 µm; C = 37 µm; D = 43 µm. R = Rome organ, W = Wouters organ.

FIGURE 5. Dentocypria mesquitai n. gen. n. sp., female (MSU. ZOC. 142). A. Mx 1. B. T 1. C. T 2. D. T 3. E. CR. F. CR attachment. Scale bar: A = 30 µm; B = 37 µm; C – E = 50 µm; F = 40 µm.

FIGURE 6. Dentocypria mesquitai n. gen. n. sp., male (MSU. ZOC. 141). A. A 2. B. right prehensile palp. C. left prehensile palp. D. hemipenis. E. Zenker organ. Scale bar: A = 44 µm; B – D = 50 µm; E = 110 µm. Arrow points to pointed process on dorsal margin of a-lobe.