Neopotamocypris indivisa, Savatenalinton, 2024

Savatenalinton, Sukonthip, 2024, A new Potamocypridini genus of Cypridopsinae (Crustacea, Ostracoda) from Thailand, with a discussion on taxonomic characters and morphological evolution in the tribe, Zootaxa 5537 (4), pp. 475-492 : 477-481

publication ID	https://doi.org/ 10.11646/zootaxa.5537.4.2
publication LSID	lsid:zoobank.org:pub:FCB0EA5F-ED89-45E8-9105-9F4942933A2D
persistent identifier	https://treatment.plazi.org/id/9D4987B6-0612-FFC0-C0C9-FF348F7D9F7F
treatment provided by	Plazi
scientific name	Neopotamocypris indivisa
status	gen. nov.

Treatment

Neopotamocypris indivisa gen. nov. sp. nov.

urn:lsid:zoobank.org:act:ACBAFC94-E72D-4B01-888D-B6B042426CDB

( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Potamocypris sp. : Savatenalinton & Suttajit, 2016: 8.

Etymology. The new species is named with regard to the outstanding character of the T 2 in which the undivided penultimate segment is apparent. The specific epithet “indivisa ” means “undivided” in Latin.

Diagnosis. RV overlapping LV ventrally, Cp in dorsal view narrow, anterior and posterior extremities pointed with subequal LV and RV margins, Cp in lateral view subtriangular, posterior margin narrowly rounded, valve surface set sparsely with long stiff, unrimmed-pore setae and long, thin, rimmed-pore setae. LV with anterior and posterior inwardly displaced selvage. RV with submarginal anterior selvage. A1 seven-segmented, Rome organ small, Wouters organ not observed. A2 natatory setae long; aesthetasc Y four-segmented with large and striated last section, A2 terminal claws well-developed. Terminal segment of Md-palp with robust claws set with (strong) setules, α seta with flagellum-like tip, γ seta markedly long with sparse setules and flagellum-like ending. Mx1-palp with spatula-shaped terminal segment bearing three large claws, a tiny seta and a robust seta, lateral subapical seta on basal segment robust with very long apical setules, lateral setae on third endite robust with very long apical setules. Apical setae on T1-endite with few setae longer than others; a, b, c, d setae absent. T2 with undivided penultimate segment, d2 seta present (d1 seta absent). T3 with pincer organ, d1 seta absent, F seta present. CR reduced with triangular base and considerably long flagellum-like apical seta, basal seta long, with thread-like tip. Female genital hook stubby with strongly curved tip.

Type materials: Holotype. Female, soft parts dissected and preserved in glycerine on a slide, and valves stored dry in a micropalaeontological slide ( MSU-ZOC.405).

Paratypes. Four dissected females ( MSU-ZOC.406, 409, 410, 413) stored like the holotype and five undissected females ( MSU-ZOC.407, 408, 411, 412, 414) stored dry in micropalaeontological slides. Whole specimens (ca. 20 individuals) kept in 70% ethanol ( MSU-ZOC.415, 416) .

Type locality. Sap Pradu Reservoir, Sikhio District , Nakhon Ratchasima Province; coordinates: 14° 51' 09" N, 101° 41' 52" E, collected on 6 February 2006, 5 October 2007 GoogleMaps .

Other localities. See Table 1.

Measurements (μm). Cp (n=5): L = 533–558, H = 282–301, W = 179–189, LV (n=3): L = 533–555, H = 262–287, RV (n=3): L = 528–542, H = 291–304.

Description

Cp in lateral view ( Fig 1A View FIGURE 1 ) subtriangular, anterior margin rounded, posterior margin more pointed than anterior margin, greatest height situated ca. at mid-length. RV overlapping LV ventrally, dorsal margin of RV higher than that of LV. Valve surface sparsely set with long stiff, unrimmed-pore setae and with long, thin, rimmed-pore setae ( Fig 1C View FIGURE 1 ).

Cp in dorsal view ( Fig 1B View FIGURE 1 ) narrowly elongated, anterior and posterior extremities pointed with subequal LV and RV margins, greatest width situated ca. at mid-length.

LV in interior view ( Figs 1D View FIGURE 1 , 2A–B View FIGURE 2 ) with anterior and posterior inwardly displaced selvages, posterior selvage with postero-ventral angulate corner, calcified inner lamella with one inner list anteriorly and posteriorly, ventral margin slightly sinuate at mid-length, greatest height situated in front of mid-length.

RV in interior view ( Figs 1E View FIGURE 1 , 2C–D View FIGURE 2 ) with marginal anterior selvage, calcified inner lamella with weak inner lists anteriorly and posteriorly, dorsal margin strongly arched, greatest height situated at mid-length, strongly sloping down to posterior margin.

A1 ( Fig 3A View FIGURE 3 ) seven-segmented. First segment with one long subapical dorsal seta (reaching mid-length of next segment) and two long apical ventral setae (subequal in length), Wouters organ not seen. Second segment slightly wider than long, with one long apical dorsal seta (reaching slightly beyond mid-length of next segment) and small Rome organ. Third segment with one long apical dorsal setae (reaching slightly beyond tip of next segment) and one short apical ventral seta. Fourth segment with two long dorsal setae and two short ventral setae (longer one reaching slightly beyond tip of next segment). Fifth segment with two long dorsal setae and two shorter ventral setae (longer one reaching mid-length of terminal segment, shorter one reaching tip of next segment). Sixth segment with four long apical setae. Terminal segment elongated with three (two long, one shorter) apical setae and aesthetasc ya, length of aesthetasc ya ca. 2/3 of shorter seta.

A2 ( Fig 3B–C View FIGURE 3 ): Basal segment with two slender proximal setae and one long slender ventro-apical seta. Exopodite with three (one long, two short) setae, the long seta reaching tip of penultimate segment. First endopodal segment with five long (reaching beyond tip of terminal claws) and one shorter accompanying setae, length of latter seta ca. 3/4 of penultimate segment, aesthetasc Y slender, four-sectioned, fourth section striated and larger than other sections, apical ventral seta long, reaching far beyond tip of terminal segment. Penultimate segment undivided, medially with two long dorsal setae (length of shorter one ca. 2/3 of that of long one) and four ventral t-setae, t2 seta longer and larger than others; this segment distally with three large, serrated claws G1, G2 and G3, claw G2 stronger serrated than claws G1 and G3, z1–z3 setae long, z1 and z2 not reaching tip of terminal claws, aesthetasc y2 short (reaching mid-length of terminal segment). Terminal segment slightly elongated with large, serrated claw GM, shorter and slender claw Gm (length ca. 2/3 of that of claw GM), and short aesthetasc y3, length of the latter ca. half of claw Gm and ca. 4/5 of that of accompanying seta, g-seta not seen.

Rake-like organ ( Fig 3E View FIGURE 3 ) T-shaped, apically with c.17 small blunt teeth.

Md-coxa ( Fig 3D View FIGURE 3 ) elongated, apically with rows of teeth (ca. 12 teeth) and small setae, largest tooth on dorsal margin and other teeth gradually decreasing in size towards ventral margin, and with cone-shaped, pointed tip subapical dorsal seta.

Md-palp ( Fig 4A–C View FIGURE 4 ): first segment with two large, hirsute S1 and S2 setae (S1seta shorter than S2 seta), one long and slender seta and a smooth, thin α-seta with flagellum-like tip. Second segment dorsally with three subequal long apical setae, one of them robust with long setules; ventrally with a group of three long, hirsute setae, one shorter seta and β-seta, the latter small, cone-shaped and slightly plumose. Penultimate segment with three groups of setae: dorsally with a group of four subequal, long, subapical setae, one of them with short setules, shortest seta thin (reaching ca. half of long ones), two long seta reaching beyond tip of terminal claws; laterally with apical γ-seta and two further apical setae; the former long, slender with slightly wide base and flagellum-like ending and with sparsely few setules, the latter smooth, thin and short; ventrally with one long apical seta (length ca. 4 times of that of terminal segment) and one short and thin seta. Terminal segment bearing three long, large, serrated claws (one of them shorter but stronger serrated than other claws) and two short setae.

Mx1 ( Fig 4D–F View FIGURE 4 ). Palp two-segmented. Basal segment of palp subquadrate with a group of five apical setae and one subapical seta; the former large, subequal and sparsely set with long setules, the latter long bearing short setules; medially of this segment with robust lateral subapical seta distally set with very long setules (reaching slightly beyond tip of terminal segment). Terminal segment spatula-shaped, apically with four (three robust, one small) claws and two (one tiny and one large) setae, large seta sparsely set with long setules. Three endites stout, third endite laterally with a group of six large setae, two of them with short setules, four setae stubby with very long setules.

T1 ( Figs 4G View FIGURE 4 ): protopodite without a, b, c, and d-setae, distally with ca. 10 hirsute apical setae, two of them obviously longer than other setae. Endopodite elongated, weakly built palp with three (two long, one short) setae, length of longest seta more than twice that of endopodite length, length of shortest seta ca. 1/5 of that of longest one.

T2 ( Fig 5A View FIGURE 5 ) with tiny d2 seta, d1 seta absent. Second segment with short e-seta (length ca. 1/3 of that of penultimate segment). Penultimate segment undivided, medially with short seta (not reaching tip of its segment), distally with a pair of apical setae (short g-seta and one tiny seta). Terminal segment dorsally bearing one short apical seta (h1), ventrally bearing one apical spine-like seta (h3) and medially with a very long and curved serrated claw seta (h2), length of h1 less than 1/7 of that of h2, length of h2 ca. that of last three segments.

T3 ( Fig 5B–C View FIGURE 5 ) with pincer organ. First segment with short d2 seta and long dp setae (length of d2 ca. 2/3 of that of dp seta), d1 seta absent, and with curved, weak sclerotized distal part. Second segment with short apical e-seta (length ca. 1/3 of that of next segment). Third segment with medially short f-seta (not reaching tip of segment) and with short subapical F seta (not reaching tip of segment). Terminal segment bearing three setae (h1-h3 setae), h1 seta short, h2 seta long, claw-like and h3 reflexed, hirsute subapical seta, h3 seta slightly longer than that of h2 seta, apical part of segment (close to base of h2 seta) with small projection.

CR ( Fig. 5D View FIGURE 5 ) reduced with triangular base, markedly long, flagellum-like apical seta and short subapical seta, the latter with thread-like tip.

Female reproductive organ with stubby genital hook ending with strongly curved tip.

Male unknown.

Ecology. Most samples of N. indivisa gen. nov. sp. nov. were collected at the depth of ca. 40–50 cm except for two localities, which were taken at ca. 90–100 cm depth. ( Table 1). The sediments were sand, mud and a small amount of organic detritus, which mostly was dead plant material, but two localities (number 4 and 6) had plenty of organic matter. No macrophyte was found in four localities (number 1, 2, 5, 9). Submerged plants found were Hydrilla verticillata (L.f.) Royle, Ottelia alismoides (L.) Pers. and Ceratophyllum demersum L. (locality number 3, 6, 8, 10), while floating plants found were Eichhornia crassipes (Mart.) Solms , Lemna perpusilla Torr. , Nymphaea pubescens Willd. and Ipomoea aquatica Forsk. (locality number 3, 4, 7). Emerged plants were found in three localities (number 4, 6, 7): Cyperus involucratus Roxb. , Typha angustifolia L. and Colocasia esculenta var. aquatilis Hassk.