Cypridopsis schwartzi, Külköylüoğlu & Veech & Tuncer, 2022

Külköylüoğlu, Okan, Veech, Joseph A. & Tuncer, Alaettin, 2022, New ostracod species (Cypridopsis schwartzi n. sp.) from Texas, with discussion on the taxonomic status of Cypridopsis species in the USA, Zootaxa 5196 (3), pp. 331-354 : 337-348

Cypridopsis schwartzi n. sp.

( Figs. 2-6 )

Diagnosis.

Carapace in dorsal view with LV overlapping RV at the margins, RV anteriorly without pustules, LV with the double folded inner list posteriorly, anteriorly margin of LV with diamond-shape ornamentations internally, LV with well-developed anteriorly calcified inner lamella. A2 with well-developed swimming setae extending the tip of the terminal claws; the 6 th seta shorter barely reaching one third of the penultimate segment. Third segment with two unequally long medium sized setae in dorsal edge, t1-2 setae very long, t3 and 4 setae not observed. T1 with b and d setae absent. Prehensile palps asymmetrical. Left palp proximally curved with a well-developed spine, right palp robust. Fingers with strong hook shaped ends. Vibratory plate with four plumose setae. Mandible with a smooth and thin alpha seta, beta seta wide hirsute, gamma seta smooth. Zenker organ with 18 whorls. Outer lobe (lobe a) of hemipenis with a well-developed protrusion internally, inner lobe with pointing end and medial lobe rounded.

Etymology. The species is named after Benjamin F. Schwartz (Texas State University) for his contributions to aquatic studies in Texas.

Type Locality. Freeman Ranch (Texas State University), San Marcos County, Texas, USA (latitude 29.937, longitude -98.002).

Material examined.

Holotype: One adult male dissected in lactophenol solution with soft body parts (no: OK-TX-OKF-1) sealed with translucent nail polish; valve kept on a micropalaeontological slide (no: OK-TX-OKF-2). Collected from the type locality on 18 May 2017 by OK and JAV.

Allotype: One adult female dissected in lactophenol solution with soft body parts from the type locality (no: OK-TX-OKF-3); valve kept on a micropalaeontological slide. Collected by OK and JAV.

Paratypes: Three males (OK-TX-OKF-4) and three females (OK-TX-OKF-5) mounted and sealed in glass slides, three carapaces kept after use for SEM (OK-TX-OKF-6), collected from the type locality; 61 females and 27 males collected from type locality.

Description.

Male: Measurements (based on midlength). L= 0.65–0.71 mm, H= 0.44–0.46 mm, W= 0.50 mm (n =4). LV overlapping RV anteriorly ( Figs. 2A ) and posteriorly ( Fig. 2 A-E, F). Carapace ovate. In dorsal view ( Fig. 2E ); posterior margin rounded, anterior margin slightly pointed. Carapace surface smooth with normal pore openings and stiff setae ( Figs. 2B, F , 3G ). Anterior margin of RV without a row of tiny pustules ( Fig. 2C ). Dorsal margin arched about the center. Pits absent or weakly present. Calcified inner lamella wider anteriorly than posteriorly ( Fig. 2C ), anterior margin with diamond-shape ornamentations internally. Posteroventral margin of LV with the double folded inner list ( Fig. 2D ). LV with internal grooves posteroventrally. Four large central and two ventral muscle scars (and two very small) located about the center ( Fig. 2F ). Eyes visible with black pigment. Color translucent to greenish without transverse bands.

Antennule (A1): Seven segmented ( Fig. 4A ): First segment (base) well-developed with a long Wouters Organ, a medium sized smooth seta on dorsal margin, and two unequally long smooth setae on ventral margin. Second segment with Rome organ short on ventral margin, dorsal-apical seta medium in size and smooth. Third segment with a long dorsal-apical seta extending halfway of the terminal segment. Fourth segment with two long dorsalapical setae, and two unequally long medium sized smooth ventral-apical setae. Fifth segment with two long dorsal setae, and one medium-sized and one long ventral-apical setae. Sixth segment with four long and smooth setae and one very short dorsal seta. Terminal segment with two long and short smooth setae and one medium-sized aesthetasc ya.

Antenna (A2): Four segmented ( Fig. 4B ). First segment with two small and smooth setae and with a mediumsized thin smooth dorsal-apical seta reaching end of the next segment. Exopodite with one long and two very small seta, first five natatory setae longer extending the tips of the claws, the 6 th seta shorter, barely reaching one third of the penultimate segment, and one well developed slightly plumose ventral-apical seta exceeding the terminal segment. Aesthetasc Y two-segmented. Third (penultimate) segment with two unequally long medium sized setae in dorsal edge, t1-2 setae unequally long and short one slightly plumose, t3 and 4 setae not observed. y2-seta very long reaching about tips of GM claw. G1 and G2 claws well developed, G3 reduced or absent. Z1-seta claw like, z2 seta-like smooth, z3-seta curved long extending tips of the claws. GM claw well-developed on terminal segment, Gm claw short about 1/3 of GM slightly serrated, and y3-seta thin about half of the Gm claw. All claws and z1-seta serrated.

Mandible (Md) ( Fig. 4C ): Coxa with eight robust teeth and three medium-sized setae internally, and dorsal seta short and stout. Palp four-segmented. First segment with vibratory plate with six well plumose setae, S1 and S2 setae plumose and unequally long. Alpha seta thin and smooth about 1/4 of S1 seta, and a long smooth seta reaching the tips of terminal claws. Second segment with ventrally a group of three unequally long smooth setae, beta seta wide, hirsute, tapering to distal end, slightly longer than alpha seta. Two of three unequally long external setae reaching tips of terminal claws, a medium-sized seta plumose barely reaching end of the next segment. Third (penultimate) segment with four unequally long and smooth external setae, two internal setae unequally long and smooth. Gamma seta smooth. Terminal segment with unequally long three claw-like setae, and three short setae.

Maxillula (Mxl) ( Fig. 5A ): Three endites and a palp with two segments, vibratory plate with 23 well-developed and plumose setae. First, second and third endites with 7 setae (2 long, 5 short), 5 setae similar in size and 6 setae (4 smooth and 2 smooth bristle-like) (not all setae illustrated in the figures), respectively. Base of first endite with two medium-sized smooth slender setae. First segment of Mx-palp with 5 setae (4 long smooth apical setae and 1 short medial seta). First segment about 3x longer than second segment. Second (terminal) segment rectangular with 4 claw-like and smooth unequally long setae.

Rake-like organ with 7-8 teeth ( Fig. 5B ).

First thoracic leg (T1) ( Figs 5 C-D): Prehensile palps asymmetrical ending with hooked-like fingers modified into clasping organs. Right palp stronger and robust. Left palp slightly longer, proximally curved and narrower than right one. Fingers ending with a strong hook shaped part. Left palp with a well-developed spine. Endite (masticatory process) with ten unequally long plumose setae. Two unequally long “a” setae present, setae b-d not observed. Vibratory plate with four long plumose setae.

Second thoracic leg (T2) ( Fig. 5E ): Five-segmented with a medium-sized plumose d2 seta on the first segment. Second, third and fourth segments with unequally long e, f, g setae slightly plumose, respectively. Terminal segment subrectangular, seta h1 short and plumose, h2 seta claw-like and extending about the last three segments and serrated. Seta h3 not observed.

Third thoracic leg (T3) ( Fig. 5F ): Three-segmented with long and smooth d1 and d2 setae, dp seta long, reaching end of the second segment. Second and third segments with slightly plumose “e” and “f” setae, respectively. Seta “e” about twice as long as “f” seta. Terminal segment separated from third segment (cf. Fig. 5F ), with h1-3 setae, h1 seta very short curved, h2 hook-like and h3 seta smooth, about as long as third segment.

Uropod: absent in males.

Zenker organ ( Fig. 6A ): with 18 whorls ending with 11 corrugated openings.

Hemipenis ( Fig. 6B ): Medium in size, outer lobe “a” with a well-developed protrusion pointing internally, inner lobe “b” with pointed end, medial lobe “h” rounded.

Color: Opaque white to light green.

Description.

Female: Carapace shape similar to that of male ( Figs. 3 A-G). Measurements: L= 0.66–0.70 mm; H= 0.43–0.44 mm; W=0.53 (n =4); G-claws (length ratio G3>G1>GM>G2≈Gm) present on A2 ( Fig. 4D ). Seta z1 thin, claw-like, setae z2-3 thin and smooth. T1 ( Fig. 6C ) normally developed, endopod with 2 short (h1-h3) and one long h2 setae (h2>h1≈h3). Seta h2 3 times as long as h1. All smooth. Endite with 10 apical setae.

Uropod ( Fig. 6D ): flagellum type (cypridopsine type) with an elongated base and one posterior seta. Genital part rounded with a genital hook inside. All other parts similar to the males.

Accompanying taxa. Physocypria gibbera (Furtos) (see Table 2 ).

Remarks: One of the aims of the present study is to compare 15 species of the genus Cypridopsis reported so far from Texas and USA. A general, but not limited, description of the new species is based on the following: carapace structure, length of swimming setae on A2, shape of hemipenis and numbers of whorls on the Zenker Organ and setae on vibratory plate of T1, and several other differences in chaetotaxy whenever possible. Several authors (e.g., Ferguson 1959; Meisch 1991; Karanovic 2012; Pérez et al. 2019) have already commented that not only the subfamily Cypridopsinae but the genera (i.e., Cypridopsis ) need to be revised because the taxonomic status of many species in the genus is still questionable (also see below). This lack of taxonomic clarity has also been an issue for us during the present study. Thereby, we thought that it was worth discussing those problems and/or specific taxonomic issues for the 15 species reported from Texas and USA. Accordingly, we compared our species with 10 other bisexual species listed in Rome (1962), Löffler (1963) and Tressler (1954). Using the length of swimming setae on A2 is a common practice in taxonomic keys for ostracods (see e.g., Meisch 2000; Karanovic 2012). Following this application, these species can be divided into two main groups based on the length of the swimming setae (natatory setae) used in the taxonomic keys (see details below).

Similar species:

Notwithstanding the species listed here, some bisexual species reported from outside of Texas and USA can be compared with the new species. In this way, two species of Rome (1962) ( C. acanthodes and C. arcuata ) have shorter or intermediate swimming setae while 10 species ( C. aequalis, Rome ; C. ellipsoidalis, Rome ; C. lacustris, Rome ; C. longa, Rome ; C. ovalis, Rome ; C. phantomensis, Tressler (see discussion); C. pseudoparva, Löffler ; C. raripila, Rome ) bear long setae extending the tips of the terminal claws. Among them, C. acanthodes is different than all others because of valve overlapping. RV overlaps LV in this species while LV> RV in others. Also, the carapace surface consists of notches in C. acanthodes whereas other species have a nearly smooth carapace surface (see C. lacustris with dorsoventral denticles). Numbers of vibratory plates on T1 is another character to compare. In four of these species ( C. ellipsoidalis , C. ovalis , C. pseudoparva , C. raripila ), the plate has four rays as is the case in C. schwartzi n. sp.. Rome (1962) underlines three rays for the females of C. ovalis but four for the males. Two bristles on Mxl are generally with two types, either smooth or denticulated. In four species ( C. acanthodes , C. arcuata , C. ovalis , C. lacustris ), bristles are smooth, similar to the new species. Shape of the hemipenis along with the numbers of whorls on Zenker Organ varies among the species, and none resembles our new species (see description above). For instance, while the shape of lobe “a” looks like a bird’s head in C. ellipsoidalis and C. raripila it is very concave in C. acanthodes , C. arcuata and C. ovalis , C. longa . The shape of lobe “a” is even reported as half-moon in C. aequalis (see Rome 1962).

Figures

FIGURE 2. Cypridopsis schwartzi n. sp. Male.A) RV external view, B) LV external view, C) RV and D) LV internal views with details of anterior and posterior margins, E) Carapace dorsal view, F) Muscle scars. A-B, holotype; C-F, paratypes. Scale 100 µm for A-E, 10 µm for F.

FIGURE 3. Cypridopsis schwartzi n. sp. Female. A) RV external view, B) LV external view, C) RV and D) LV internal views, E) Carapace dorsal view, F) Carapace ventral view, G) Pore openings with setae. A-B, allotype; C-F, paratypes. Scale 100 µm for A-F, 10 µm for G.

FIGURE 4. Cypridopsis schwartzi n. sp. Male (Holotype): A) A1, B) A2, C) Md, D) A2 of female (Allotype). Scale: 100 μm.

FIGURE 5. Cypridopsis schwartzi n. sp. Male (Holotype): A) Mx1, B) Rake-like organ, C) Right clasping organ, D) Left clasping organ, E) T2, F) T3. Scale: 100 μm.

FIGURE 6. Cypridopsis schwartzi n. sp. A) Zenker Organ, B) Hemipenis, C) T1 of female, D) Uropod and genital organ of female. A-B, holotype; C-D, allotype. Scale: 100 μm.