Cyprinotus drubea, Martens & Higuti, 2019

Martens, Koen & Higuti, Mehmet Yavuzatmaca and Janet, 2019, On a new species of the genus Cyprinotus (Crustacea, Ostracoda) from a temporary wetland in New Caledonia (Pacific Ocean), with a reappraisal of the genus, European Journal of Taxonomy 566, pp. 1-22 : 6-14

Cyprinotus drubea sp. nov.

urn:lsid:zoobank.org:act:D5A779FF-547B-4702-9F99-F64E8E257210

Figs 2–7

Diagnosis

A species typical of the genus, with the larger LV overlapping the RV along the anterior, ventral and posterior margins and with anterior and posterior margins of the RV set with row of strong tubercles. RV dorsally overlapping LV with a very large, rounded hump, which is dorsally skewed to the right and posterior sides and is lined by a ridge. LV rather elongated (L/H ratio = 1.79).

Etymology

The species is named after the Drubea Kapone customary area.

Material examined

Holotype

NEW CALEDONIA • ♀, with soft parts dissected in glycerine in a sealed slide and with valves stored dry in a micropaleontological slide; Grande Terre, Province Sud, north of Tontouta airport, commune de Paita ; approx. coordinates 21°59′18.5″ S, 66°12′25.4″ E; ca 9 m a.s.l.; 7 Jun. 2018; J. Higuti and K. Martens leg.; sample HYNC 3065 ; pH = 7.56; electrical conductivity = 831 µS / cm; water temperature = 22.3°C; accompanying ostracod fauna – Stenocypris major (Baird, 1859) , Cypris granulata (Daday, 1910) , Kennethia major ( Méhes, 1939) and several as yet unidentified species in Cypretta , Candona s. lat., Stenocypris and ‘ Gomphocythere ’; MNHN-IU-2019-784 .

Paratypes

NEW CALEDONIA • 2 ♀♀, with soft parts dissected as the holotype but with valves lost; same collecting data as for holotype; MNHN-IU- 2019-2541, MNHN-IU- 2019-2542 • 2 ♀♀; same collecting data as for holotype; MNHN-IU-2019-782, MNHN-IU-2019-783 • 2 ♀♀; same collecting data as for holotype; RBINS-INV.156000/ OC.3400, RBINS-INV.15600/ OC.3401 • 3 A- 1 ♀♀, with valves and carapaces stored dry after use for SEM illustrations; same collecting data as for holotype; MNHN-IU-2019-779, MNHN-IU-2019-780, MNHN-IU-2019-781 • 1 A- 1 ♀, with valves and carapace stored dry after use for SEM illustrations; same collecting data as for holotype; RBINS-INV.156002/ OC.3402 • ca 10 ♀♀ and 10 A- 1 ♀♀ in toto in EtOH; same collecting data as for holotype; MNHN-IU- 2019-2313 • ca 10 ♀♀ and 10 A- 1 ♀♀ in toto in EtOH; same collecting data as for holotype; RBINS-INV.156003/OC.3403 .

Measurements (all in µm)

Holotype (adult female)

MNHN-IU-2019-784: RVi/ L = 1.079; H = 782; LVi/ L = 1.153; H = 671.

Paratypes (adult females)

MNHN-IU-2019-783: CpRL/ L = 1.144; H = 756.

RBINS-INV.156000/OC.3400: CpLL/ L = 1.128; H = 796.

MNHN-IU-2019-782: CpD / L = 1.171; W = 521.

RBINS-INV.156001/OC.3401: CpV / L = 1.203; W = 525.

Paratypes (A- 1 juvenile females)

MNHN-IU-2019-781: CPRL / L = 915; H = 519.

MNHN-IU-2019-780: CpD / L = 898; W = 374.

MNHN-IU-2019-779: CpLL/L = 888; H = 508.

RBINS-INV.156002/OC.3402: RVi /L = 867; H = 511; LVi/ L = 894; H = 526.

Description

Adult female

LVI ( Fig. 2A ). With evenly rounded anterior and bluntly pointed posterior margin. Dorsal margin bluntly pointed and with greatest height situated well in front of the middle. Calcified inner lamellae narrow on anterior and posterior sides; these margins with a tuberculated selvage ( Fig. 2 G–H). Posterior part of valve slightly protruding beyond postero-ventral valve margin ( Fig. 2H ).

RVI ( Fig. 2B ). With evenly rounded anterior margin and almost straight, sloping posterior margin. Dorsally with a very large and rounded hump, slightly leaning backwards. Calcified inner lamellae narrow on anterior and posterior sides; these margins set with a row of strong tubercles ( Fig. 3 A–B). Anterior margin furthermore with a sub-marginal selvage, marginal tubercles caught between this selvage and the valve margin ( Fig. 3A ). Posterior margin with clearly inwardly displaced selvage, the latter leaving the tubercles largely free ( Fig. 3B ).

CP. CpRL ( Fig. 2C ) clearly showing larger LV overlapping RV along anterior and posterior margin, and to a lesser extend along ventral margin. CpLL ( Fig. 2D ) showing extend to which dorsal hump on RV overlaps LV. External surface of both valves densely pitted and set with short setae in rimmed pores ( Fig. 3C ). CpD ( Fig. 2E ) showing the rostrum-like anterior part of the Cp and the shape of the humplike expansion of the RV; the latter leaning toward the right side and the dorsal edge being set with a ridge ( Fig. 3D ). CpV ( Fig. 2F ) also showing anterior rostrum ( Fig. 3E ) and weakly developed flap-like expansion of LV overlapping RV ( Fig. 3F ).

A1 ( Fig. 4A ). 7-segmented. First segment large, with two long ventral and one short dorsal setae; Wouters organ not seen. Second segment with one apical seta on the dorsal side, reaching beyond middle of third segment: Rome organ very small and indistinguishable. Third segment ca twice as long as second segment, carrying one shorter ventral and one longer dorsal apical setae. Fourth and fifth segments all with four long apical natatory setae, two ventral and two dorsal, but dorsal ones much longer than ventral ones. Sixth segment with four long and one shorter setae. Final segment with two long natatory setae, one shorter seta and an aesthetasc Ya, the latter ca half the length of the shorter apical seta.

A2 ( Fig. 4 B–C). Typical of the subfamily. First segment with three basal setae on the ventral side and with one long ventro-apical seta, the latter reaching beyond tip of terminal segment. Endopodite consisting of a small plate with one long and two unequal short setae. First endopodal segment with basally inserted aesthetasc, distally with five long and one short natatory setae, long setae reaching with about 1 ∕ 5 of their length beyond the tips of the endclaws, and one stout and long ventro-apical seta, reaching till the middle of the endclaws. Second endopodal segment with two unequal setae inserted mid-dorsally and four unequal setae, inserted mid-ventrally, apically with three long z-setae (reaching beyond tips of endclaws) and claws G1, G2 and G3, G2 being the shortest. Terminal segment with one large claw GM, one shorter claw Gm (ca half the length of GM), seta g almost as long as claw Gm and an aesthetasc y3, fused with an accompanying seta over a short distance, the accompanying seta being ca twice the length of the aesthetasc and ¾ of the length of seta g.

MD. Md-palp ( Fig. 5A ) with four segments. First segment large, with a respiratory plate bearing five long and one short setae; ventro-distally with one long smooth seta, a long, thin and smooth α-seta and two setose s-setae. Second segment with a group of three long setae, inserted mid-dorsally and a group of five ventral setae: three thin and relatively long setae, setose in their distal third, one stout, shorter seta and one short, but stout β-seta. Third segment with a dorso-subapical group of four setae; a row of four apical setae, three thin and relatively short setae and one stout and claw-like γ-seta, dorsally inserted; and two ventro-subapical setae, one long and one very short. Terminal segment about as long as basal width, tapering, set with four apical claws and one seta. Md coxa ( Fig. 5B ) elongated, distally with ca 10 teeth, interspaces with small setae, and one short subapical seta.

MX 1 ( Fig. 5 C–D). Consisting of a two-segmented palp, three endites and a vibratory plate for respiration. First palp segment with five apical setae, one of which plumose, one long and one short subapical setae. Second palp segment rectangular, ca twice as long as basal width, apically carrying three claws and three setae. Third endite with two large, distally serrated setae (“Zahnbürsten”). First endite with one apical side-ways directed bristle and two basal setae. Vibratory plate with ca 12 distal rays and an additional six basal setae.

T1 ( Fig. 6A ). With an elongated palp, carrying three apical setae, the middle one (h2) being the longest. Respiratory plate with five long and one short rays. Protopodite with two short but unequal a-setae, a short b-seta, a longer d-seta, almost twice as long as b-seta and distally with 11 (sub-) apical setae of unequal length.

T2 ( Fig. 6B ). A walking leg. First segment with short seta d1. Second segment (knee-segment) without seta d2. Third segment long, ca three times as long as wide, carrying a distal e-seta, reaching just to tip of segment 4a. Fourth segment divided in two parts. Segment 4a with apical f-seta reaching tip of segment 4b. Segment 4b with apically inserted seta g and a very short second seta. Terminal segment with curved claw h2 and two flanking setae, seta h1 longer than seta h3, the latter subapical.

T3 ( Fig. 6 C–D). A cleaning leg. First segment with three long setae (d1, d2 and dp). Second segment elongated, about five times as long as wide, distally with a long e-seta, reaching beyond tip of limb. Third segment shorter, with medially inserted f-seta, also reaching beyond tip of limb. Distal part of third segment fused with fourth segment, forming a pincer, with a long seta h3, a curved hook-like seta h2 and a minuscule seta h1 (not shown).

CR ( Fig. 6E ). Elongated, with broad basal part. Proximal claw Gp ca ½ the length of distal claw Ga; proximal seta Sp almost as long as distal seta Sa. Attachment of caudal ramus ( Fig. 6F ) a single narrow and curved ramus.

RAKE- LIKE ORGAN ( Fig. 6G ). With narrow rod and distally with eight blunt teeth.

A- 1 juvenile female

LV ( Fig. 7A ). With shape similar to that in adults, greatest height situated well in front of the middle; both posteriorly ( Fig. 7H ) and anteriorly ( Fig. 7I ) with large selvage; calcified inner lamella narrow.

RV ( Fig. 7B ). With similar outline, but with much smaller postero-dorsal hump than in the adult.Anterior ( Fig. 7F ) and posterior margins with narrow calcified inner lamella; no inwardly displaced selvages. Marginal tubercles absent, or very small.

CPD ( Fig. 7E ). Rather narrow, with LV overlapping RV anteriorly and posteriorly; greatest width situated in the middle.

CPRL ( Fig. 7C ). With LV overlapping RV anteriorly and posteriorly; along dorsal margin RV extending beyond LV in posterior part, LV extending beyond RV in anterior part. External surface of Cp strongly ornamented, with tightly intertwined ridges, resulting pits and rimmed pores with long setae ( Fig. 7G ).

CPLL ( Fig. 7D ). With RV only slightly extending past LV in posterior part of the dorsal margin.

A2. With five long natatory setae and without the shorter seta. Remark: this is typical of the A- 1 juveniles in Cyprididae ; the accompanying short seta only forms in the last moult to the adult stage (not illustrated).

Differential diagnosis

The new species can at once be distinguished from all other extant species in the genus by the large and rounded dorsal hump on the RV; this hump is much smaller in most other species of Cyprinotus . Some specimens of Cyprinotus with a large dorsal hump from wells in the Pilbara region (northern Western Australia) were illustrated and erroneously identified as C. cingalensis by Karanovic (2008). However, the hump in the latter species is wider, less high and distally less rounded. Also, the ventro-caudal side of the LV in the specimens from the Pilbara is more rounded, while the LV as such is less elongated (L/ H ratio in Pilbara specimens = 1.70; L/ H ratio in C. drubea sp. nov. = 1.79). The dorsal helmet of the new species is also larger than in the fossil C. scholiosus ( Sohn & Morris, 1963) and the LV of the former is also slightly more elongated (L/ H ratio in Sohn & Morris (1963) = 1.62, in Malz (1976) = 1.71; L/ H ratio in C. drubea sp. nov. = 1.79).

Ecology and distribution

All species in this genus are typical of temporary habitats and C. drubea sp. nov. is no exception. The species was found in a shallow temporary marsh, covering several hectares, which was densely covered with grasses and species of Juncus L.

Figures

Fig. 2. Scanning Electron Microscope images of Cyprinotus drubea sp. nov., ♀♀. A. LVi (MNHN- IU-2019-784). B. RVi (MNHN-IU-2019-784). C. CpRL (MNHN-IU-2019-783). D. CpLL (RBINS- INV.156000/OC.3400). E. CpD (MNHN-IU-2019-782). F. CpV (RBINS-INV.156001/OC.3401). G. LVi, detail of anterior part (MNHN-IU-2019-784). H. LVi, detail of posterior part (MNHN- IU-2019-784). Arrows indicate anterior side. Scale bars: A–F = 500 µm; G = 400 µm; H = 200 µm.

Fig. 3. Scanning Electron Microscope images of Cyprinotus drubea sp. nov., ♀♀. A. RVi, detail of anterior part (MNHN-IU-2019-784). B. RVi, detail of posterior part (MNHN-IU-2019-784). C. CpRL, detail of carapace surface (MNHN-IU-2019-783). D. CpD, detail of hump (MNHN-IU-2019-782). E. CpV, detail of anterior part (RBINS-INV.156001/OC.3401). F. CpV, detail of central overlap (RBINS-INV.156001/ OC.3401). Arrows indicate anterior side. Scale bars: A, D–E = 200 µm; B = 400 µm; C, F = 100 µm.

Fig. 4. Cyprinotus drubea sp. nov., ♀♀. A. A1 (MNHN-IU-2019-2542). B. A2 (MNHN-IU-2019-2541). C. Detail of apical chaetotaxy of A2 (MNHN-IU-2019-2542). Scale bar: A = 344 µm; B = 135 µm; C = 46 µm.

Fig. 5. Cyprinotus drubea sp. nov., ♀♀. A. Md-palp (MNHN-IU-2019-2541). B. Md-coxa (MNHN- IU-2019-2541). C. Palp and endites of Mx1(chaetotaxy of endites not complete)(MNHN-IU-2019-2541). D. Vibratory plate of Mx1 (MNHN-IU-2019-2542). Scale bar: A = 101 µm; B, D = 139 µm; C = 84 µm.

Fig. 6. Cyprinotus drubea sp. nov., ♀♀. A. T1 (MNHN-IU-2019-2542). B. T2 (MNHN-IU-2019-2541). C. T3 (MNHN-IU-2019-2541). D. Detail of apical pincer of T3 (MNHN-IU-2019-2541). E. CR (MNHN-IU-2019-2542). F. Attachment of CR (MNHN-IU-2019-2542). G. Rake-like organ (MNHN- IU-2019-2542). Scale bar: A = 111 µm; B = 93 µm; C = 106 µm; D = 42 µm; E–F = 127 µm; G = 104 µm.

Fig. 7. Cyprinotus drubea sp. nov., ♀♀ A-1 juveniles. A. LVi (INV.156002/OC.3402). B. RVi (RBINS- INV.156002/OC.3402. C. CpRL (MNHN-UI-2019-781). D. CpLL (MNHN-UI-2019-779). E. CpD (MNHN-UI-2019-780). F. RVi, detail of anterior part (RBINS-INV.156002/OC.3402). G. CpRL, detail anterior (MNHN-UI-2019-781). H. LVi, detail of posterior part (RBINS-INV.156002/OC.3402). I. LVi, detail of anterior part (RBINS-INV.156002/OC.3402). Arrows indicate anterior side. Scale bars: A–E = 500 µm, F = 400 µm, G–I= 100 µm.