Martensina thailandica, Savatenalinton, 2022

Savatenalinton, Sukonthip, 2022, Martensina thailandica gen. et sp. nov. a freshwater ostracod representing a new subfamily of Cyprididae, Martensininae subfam. nov. (Crustacea: Ostracoda) from Thailand, European Journal of Taxonomy 836 (1), pp. 1-22 : 4-15

Martensina thailandica gen. et sp. nov.

urn:lsid:zoobank.org:act:891B468F-543D-4355-9D98-B5D8D4C37C4C

Figs 1–8

Diagnosis

Cp large (ca 1.5 mm length), Cp in lateral view rounded with greatest height situated at mid-length, anterior and posterior margins strongly curved to dorsal margin, Cp in dorsal view narrow with greatest width ca mid-length. A1 7-segmented, terminal segment very elongated, aesthetasc ya extraordinary long (reaching tip of long seta), Rome organ present, Wouters organ not seen. A2 natatory setae long, terminal segment markedly long (length ca five times of width), male A2 with markedly short Gm claw. Md-palp with elongated penultimate segment, terminal segment with two claws and one seta, α- and β-setae short and slim. Terminal segment of Mx1-palp elongated with one large claw and four slender setae, two large bristles on 3 rd endite smooth. Prehensile palps 2-segmented, right palp with large, subtriangular terminal segment, terminal segment of left palp strongly hook-like and with pointed projection on outer margin. T2 basal segment with d1 and d2 setae, d1 seta very long (ca two times as long as d2 seta), penultimate segment divided, h2 claw with robust apical spinules in male. T3 terminal segment distinctly separated with three long setae, d1 and dp setae present (d2 seta absent). CR well developed with short Sa seta, Sp seta short and claw-like situated close to Gp claw. Hp with large ms and ls, distal margins widely rounded, and with reticulated structure on outer part of main lobe. Zenker organ with 23 spiny whorls and funnel-shaped at both ends.

Differential diagnosis

As Martensina gen. nov. is presently monospecific, the differential diagnosis is the same for the genus.

Etymology

The species is named after Thailand, where the new species was discovered.

Type material

Holotype THAILAND – Maha Sarakham Province  ♂ (soft parts dissected in glycerine on a sealed glass slide and valves stored dry in a micropalaeontological slide); Nong Bua (swamp), Kantharawichai District ; 16.320841º N, 103.296405º E; 22 Oct. 2021; MSU-ZOC.317 .

Allotype THAILAND – Maha Sarakham Province  ♀ (stored as the holotype); same collection data as for holotype; MSU-ZOC.318 .

Paratypes THAILAND – Maha Sarakham Province  5 ♂♂ (stored as the holotype), 4 ♂♂ (carapaces stored dry in micropalaeontological slides); same collection data as for holotype; MSU-ZOC.319 to ZOC.327 • 5 ♀♀ (stored as the holotype), 3 ♀♀ (carapaces stored dry in micropalaeontological slides); same collection data as for holotype; MSU-ZOC.328 to ZOC.335 .

Type locality

A total of 28 female and 20 male specimens were collected at the type locality on 22 Oct. 2021. Accompanying ostracod fauna: Bradleystrandesia weberi (Moniez, 1892) , Cypretta aculeata Savatenalinton, 2018 , Dentocypria mesquitai Savatenalinton, 2017 , Dentocypria chantaranothaii Savatenalinton, 2017 , Fabaeformiscandona subacuta (Yang, 1982) , Pseudocypretta maculata Klie, 1932 , Pseudostrandesia mamarilorum (Victor & Fernando, 1981) , Pseudostrandesia striatoreticulata (Klie, 1932) , Pseudostrandesia cf. calapanensis, Stenocypris sp. , Strandesia kraepelini (Müller, 1906) , Thaicypridopsis longispinosa Savatenalinton, 2018 , Vestalenula sp.

Repository

The type specimens are deposited in the ostracod collection in the Faculty of Science, MSU (Maha Sarakham, Thailand).

Description

Male

MEASUREMENTS (in μm). Male. Cp (n = 5), L = 1335–1413, H = 787–813, W = 523; LV (n = 1), L = 1387, H = 845; RV (n = 1), L = 1394, H = 839.

CP. In dorsal view ( Fig. 1A ) elongated, greatest width situated at mid length, RV slightly overlapping LV anteriorly, anterior extremity slightly compressed, posterior extremity narrowly rounded, hinge adont. Cp in ventral view ( Fig. 1B ): LV overlapping RV ventrally. Cp in lateral view ( Fig. 1C–D ) subglobular (length ca 1.4 mm), greatest height situated at mid length, dorsal margin strongly arched, ventral margin sinuated at mid length, anterior and posterior margins widely rounded. Valve surface ( Fig. 1E ) scattered with shallow pits and rimmed-pore setae. No pigmentation on valve surface.

LV. In internal view ( Fig. 2A, C–D ) with both valve margins rounded, slightly wider rounded posteriorly, dorsal margin strongly arched, ventral margin sinuate in front of mid length, marginal selvage anteriorly and posteriorly, anterior calcified inner lamella wide without inner list, posterior calcified inner lamella narrow without inner list. Muscle scars comprising two mandibular muscle scars and a group of adductor muscle scars. The latter group not tightly arranged.

RV. In internal view ( Fig. 2B, E–F ) with both valve margins rounded, slightly wider rounded posteriorly, dorsal margin strongly arched, ventral margin sinuate, submarginal selvage anteriorly, marginal pore canals present anteriorly, calcified inner lamella wide anteriorly, narrow posteriorly, without anterior and posterior inner lists.

A1 ( Fig. 4A ). Seven-segmented, first segment with one long dorso-subapical seta (reaching tip of next segment), two long ventro-apical setae, Wouters organ not seen. Second segment ca 1.5 times as wide as long, with one very short dorso-apical seta (ca ¼ of next segment) and small Rome organ. Third segment bearing two setae: one short dorso-apical (reaching mid-length of next segment) and one short ventroapical setae (reaching mid-length of next segment). Fourth segment with two long dorsal setae and two shorter ventral setae (shortest one reaching beyond mid-length of next segment). Fifth segment dorsally with two long setae, ventrally with two (one long, one shorter) setae, shorter one reaching beyond tip of next segment. Penultimate segment with four long apical setae. Terminal segment with three (two long, one short) apical setae and remarkably long aesthetasc ya, short seta ca half as long as long seta, length of aesthetasc ya almost same as that of long seta).

A2 ( Fig. 4B ). Basal segment with two proximal setae and one long ventro-apical seta. Exopodite with three (one longer, two short) setae, longer one not reaching half of first endopodal segment. First endopodal segment with five long natatory setae (reaching tips of terminal claws) and one short accompanying seta (length ca ¼ that of penultimate segment), aesthetasc Y short and thin, situated at ca ⅓ of its segment length, ventro-apical seta long, extending far beyond tip of penultimate segment. Penultimate segment undivided, distally with claw-like z1 and z2 setae (almost same length), z3 seta long, reduced claw G1 and G2 and with claw G3 considerably reduced to thin setae, claw G1 and G2 with stronger teeth than other claws, aesthetasc y2 long (almost reaching mid-length of terminal segment); this segment medially with two subequally short dorsal setae, four ventral setae of unequal length (t1–4) and small y1. Terminal segment markedly elongated, distally with two serrated claws (GM and Gm), claw Gm considerably reduced (length of Gm ca half of that of GM), markedly long aesthetasc y3 (almost reaching tip of claw GM) and accompanying seta (reaching mid-length of aesthetasc y3), g-seta not seen.

MD- COXA ( Fig. 5A ). Elongated, distally with rows of teeth and small setae, and with one long, slender dorso-subapical seta.

MD- PALP ( Fig. 5B –B’). First segment with two setae (S1 and S2), one long and slender seta, and α-seta, the latter smooth and very short. Second segment dorsally with three unequal long apical setae, shortest seta reaching mid-length of next segment; ventrally with group of three long setae, one shorter seta and smooth, short and thin β-seta. Penultimate segment bearing three groups of setae: dorsally with group of four unequal, long, subapical setae; laterally with thin, long apical γ-seta (ca 2 times as long as terminal segment) and three further apical setae subequal in length (ca 1.7 times as long as terminal segment); ventrally with two subapical setae, one long (length ca two times that of terminal segment), one short (reaching slightly tip its segment). Terminal segment bearing two large claws and one seta, length of terminal claws ca 2.2 times that of terminal segment. All setae on Md-palp set with tiny setules.

RAKE- LIKE ORGAN. Stout, T-shape with eight blunt teeth.

MX 1 ( Fig. 5C ). With two-segmented palp, basal segment of palp dorsally with group of four long, unequal apical setae; terminal segment elongated, apically with one claw and four setae. Two large bristles (Zahnborsten) on third endite smooth. Two sideways-directed bristles on first endite long, subequal in length. Respiratory plate large, semicircular shape comprising six reflexed setae on anterior margin and a number of long, setulous setae along posterior and ventral margins.

T1 ( Fig. 6A–C ). Protopodite with two a-setae, subequal in length and long b-and short d-setae, c-seta absent; distally with nine hirsute apical setae of unequal length and five subapical setae. Endopodite large and very elongated, 2-segmented, forming asymmetrical prehensile palps, right palp ( Fig. 6A ) with one subapical spine and apical protrusion on basal segment, terminal segment subtriangular; left palp ( Fig. 6B ) with one subapical spine and blunt-tip apical protrusion on basal segment, terminal segment strongly hook-like with small pointed projection on outer margin of hook corner. Respiratory plate with six hirsute setae.

T2 ( Fig. 6E ). On first segment with d1 and d2 setae long, subequal in length. Second segment with long e-seta (reaching beyond mid-length of penultimate segment). Penultimate segment divided, medially with f-seta (reaching beyond tip of terminal segment), distally with apical short g-seta and one very short accompanying seta (length ca ⅓ that of g-seta). Terminal segment with two (one dorsally, one ventrally) short apical h1 and h3 setae and serrated claw (h2), distal part of h2 with strong spine-like setules.

T3 ( Fig. 7A ). First segment with d1 and dp setae subequal in length (d2 seta absent). Second segment with long apical e-seta (reaching tip of next segment). Third segment with f-seta (almost reaching tip of segment), g-seta absent. Terminal segment without pincer organ and bearing three long setae (h1–h3 setae), all subequal in length.

CR ( Fig. 7C ). Symmetrical with well-developed claws and setae, claw Ga long (length ca half of that of ramus), claw Ga long (ca half length of ramus), claw Gp short (ca half length of claw Ga), Sa seta very short (ca ¼ of claw Gp), Sp seta short and robust (claw-like) (reaching tip of ramus). CR attachment ( Fig. 7B ) thin with two branches distally.

HP ( Fig. 7D ). With ms and ls large, widely rounded distal margins (lateral shield wider), without protrusion and with strong muscles; proximal part of ms with reticulated structure on outer margin; postlabyrinthal spermiduct curved, copulatory process with pointed tip. Zenker organ ( Fig. 7E ) elongated and set with 23 spiny whorls, proximal and distal ends funnel shaped.

Female

MEASUREMENTS (in μm). Cp (n = 4), L = 1374–1497, H = 871–903, W = 613; LV (n = 1), L = 1510, H = 890; RV (n = 1), L = 1542, H = 923.

Carapace and valves as in male, although somewhat bigger (length ca 1.5 mm) ( Figs 1F–I , 2G–H , 3 ). All limbs as in male, except for last two segments of A2, T1, and T2. Penultimate segment of A2 ( Fig. 4C ) with two large, serrated claws G1 and G3, claw G2 shorter and slenderer than claws G1 and G3, z1– z3 long, z1 and z3 subequal in length (almost reaching tip of claw G3). Terminal segment with large, serrated claws GM and Gm (length of claw Gm ca 5/6 that of claw GM), aesthetasc y3 markedly long (reaching slightly beyond tip of claw Gm), and accompanying seta (reaching mid-length of aesthetasc y3), g-seta not seen. T1-endopodites ( Fig. 6D ) elongated, weakly built palp with three (one long, two shorter) apical setae, long one ca two times as long as short one. T2 ( Fig. 8A ) same as in male, except for distal part of claw h2 being serrated, without strong spine-like setules. T3 ( Fig. 8B ) same as in male, except for tips of e and f setae being more pointed. CR ( Fig. 8C ) same as in male, except for slightly shorter ramus. Genital lobe rounded, without any extension.

Ecology

The new taxon was collected from the sediment surface in the littoral zone of the swamp, close to the village. The sampling site was densely covered by a number of aquatic plants, particularly lotus. The sediment was largely composed of organic matter, especially dead plant material.

Figures

Fig. 1. Martensina thailandica gen. et sp. nov., paratypes. A–E. Males. F–I. Females. A. Cp, dorsal view (MSU-ZOC.321). B. Cp, ventral view (MSU-ZOC.324). C. Cp, left lateral view (MSU-ZOC.322). D. Cp, right lateral view (ditto). E. Cp, left lateral view, valve surface (ditto). F. Cp, left lateral view, valve surface (MSU-ZOC.330). G. Cp, dorsal view (MSU-ZOC.329). H. Cp, left lateral view (MSU- ZOC.330). I. Cp, right lateral view (ditto). Scale bars: A–D, G–I = 200 μm; E–F = 10 μm.

Fig. 2. Martensina thailandica gen. et sp. nov. A–F. Paratype, ♂ (MSU-ZOC.319). G–H. Allotype, ♀ (MSU-ZOC.318). A. LV, internal view. B. RV, internal view. C. LV, internal view, posterior part. D. LV, internal view, anterior part. E. RV, internal view, anterior part. F. RV, internal view, posterior part. G. LV, internal view. H. RV, internal view. Scale bars: A–B, G–H = 200 μm; C–F = 100 μm.

Fig. 3. Martensina thailandica gen. et sp. nov., allotype, ♀ (MSU-ZOC.318). A. LV, internal view, posterior part. B. LV, internal view, anterior part. C. LV, internal view, muscle scars. D. RV, internal view, anterior part. E. RV, internal view, posterior part. Scale bars: A–B, D–E = 100 μm; C = 50 μm.

Fig. 4. Martensina thailandica gen. et sp. nov. A–B. Holotype, ♂ (MSU-ZOC.317). C. Allotype, ♀ (MSU-ZOC.318). A. A1. B. A2. C. A2, last two segments. Scale bars = 100 μm.

Fig. 5. Martensina thailandica gen. et sp. nov., holotype, ♂ (MSU-ZOC.317). A. Md-coxa. B. Md-palp. B’. Md-palp, α, β, γ setae. C. Mx1. Scale bars: A–B = 100 μm; C = 50 μm.

Fig. 6. Martensina thailandica gen. et sp. nov. A–C, E. Holotype, ♂ (MSU-ZOC.317). D. Allotype, ♀ (MSU-ZOC.318). A. Right T1. B. T1, left prehensile palp. C. T1 protopodite. D. T1 endopodite. E. T2. Scale bars: A–B, D–E = 100 μm; C = 50 μm.

Fig. 7. Martensina thailandica gen. et sp. nov. A–B, D. Holotype, ♂ (MSU-ZOC.317). C, E. Paratype, ♂ (MSU-ZOC.319). A. T3. B. CR attachment. C. CR. D. Hemipenis. E. Zenker organ. Arrow indicates reticulated structure. Scale bars = 100 μm.

Fig. 8. Martensina thailandica gen. et sp. nov., allotype, ♀ (MSU-ZOC.318). A. T2. B. T3. C. CR. Scale bars = 100 μm.