Indocandona rusti, Külköylüoğlu & Hutchins & Yavuzatmaca & Schwartz, 2021

Külköylüoğlu, Okan, Hutchins, Benjamin T., Yavuzatmaca, Mehmet & Schwartz, Benjamin F., 2021, Hyporheic ostracods (Crustacea, Ostracoda) from Texas (USA) with six new species, Zootaxa 5046 (1), pp. 1-63 : 32-37

Indocandona rusti n. sp.

( Figs 19–22 )

Type locality. Independence Creek at County Road 349, Terrell County, Texas, USA (Lat: 30.460 322, Long: - 101.825467), Elevation ~ 618 m ASL .

Etymology. The species is named after emeritus Prof. Dr. Richard W. Rust (formerly at University of Nevada, Reno, USA) in recognition of his tremendous works and outstanding contributions in entomology and for his longlasting friendship with the first author.

Material examined. Holotype. Male dissected in lactophenol solution with soft body parts slide mounted and sealed with translucent nail polish (no: OK-TX-InCr-150713 H1-1); valve kept in micropalaeontological slide (no: OK-TX-InCr-150713 H1-2). Collected from type locality on 13 July 2015 by Benjamin T. Hutchins and Danielle Belleny.

Allotype: One female from the type locality (no: OK-TX-InCr-150713 H1-3). Collected by Benjamin T. Hutchins and Danielle Belleny.

Dissected paratype s. One male (no: OK-TX-InCr-150713 H1-4) and three females (no: OK-TX-InCr-150713 H1-5-7) dissected in lactophenol solution with soft body parts sealed with translucent nail polish. Collected from type locality by Benjamin T. Hutchins and Danielle Belleny.

Non-dissected paratypes. Four females, one male, and three juveniles kept in 70% ethanol. Collected from type locality by Benjamin T. Hutchins and Danielle Belleny.

Repository. The holotype and all paratypes are stored at the Limnology Laboratory of the Biology Department, Bolu Abant İzzet Baysal University, Bolu, Turkey .

Description: Measurements (in μ m). Male (n=4): LV: L=510–523 (mean = 520), H=201–210 (mean = 205); RV: L=500–510 (mean = 510), H=200–205 (mean = 200); W=130–135 (mean = 134). Female (n=4): LV: L=510– 525 (mean = 520), H=200–225 (mean = 510); RV: L=510–520 (mean = 515), H=200–215 (mean = 210); W=130– 134 (mean = 132).

Carapace ( Fig. 19 ) opaque to white, surface with long longitudinal lines, elongated, sharply pointed posteriorly, rounded anteriorly, greatest height just in front of center, dorsal margin rounded, ventral margin slightly convex. LV overlapping RV posteriorly, dorsally and ventrally. RV slightly longer antero-dorsally. Hinge adont. Calcified inner lamella wide anteriorly and posteriorly. Uncalcified part wide. Muscle scars not apparent externally.

A1 ( Fig. 20A ): Seven-segmented. Wouters and Rome organs not apparent. First segment with two smooth ventral setae reaching tip of terminal segment. Second and third segments without setae. Fourth and fifth segments with two smooth equally long setae. Penultimate segment with three setae. Terminal segment with two smooth apical setae and aesthetasc ya, about ¾ length of the two setae.

A2 ( Fig. 20B ): Five-segmented. First segment with one basal seta. Exopodial plate with two very short setae (difficult to see). Second segment with one long seta, aesthetasc Y about as long as segment and one medium size posterior seta. Natatory setae absent. Penultimate segment divided, third segment with two claw-like t-setae and two smooth posterior setae (longest widened basally), penultimate segment with two unequally long z-setae (z1 about 2x length of z2) and two claws (G1, G2) well developed and serrated, claw G3 very short, seta-like, about size of terminal segment, G1 claw ends with sharp pointed end. Terminal segment with GM claw, a seta-like Gm, aesthetasc y3 long and seta-like.

Md-palp ( Fig. 20C ): Md-coxa with 5–6 strong teeth and pointed end. First segment with two plumose S-setae (S1 slightly longer than S2), one smooth seta and a short alpha seta. Vibratory plate with five smooth, unequally long setae. Second segment with group of three smooth setae. Beta seta not apparent. Penultimate segment with three dorsal setae (most apical one claw-like), smooth gamma seta, and three short apical setae. Terminal segment square and fused with central claw.

Mx1 ( Fig. 20D ) with three endites and Mx1-palp. First endite slender, with five short setae. Second and third endites with five and six setae, respectively. Third endite with two smooth bristles. Vibratory plate with short setae (not shown in figure). First palp with two equally long setae about twice the length of second palp. Second palp subrectangular or subtriangular, with four smooth claw-like setae.

T1 ( Figs. 21A, B ): Transformed into asymmetrical, prehensile palps. Setae a, c, and d not apparent, b seta short. Vibratory plate without setae. Right prehensile palp enlarged ventrally and curved, with two apical spines, left palp thin, without spine. Left prehensile palp thinner, ending with a hook-shaped process.

T2 ( Fig. 21C ): Five-segmented, with one long h2 and very short h1 seta on terminal segment. Other segments without setae.

T3 ( Fig. 21D ): Five-segmented. First segment with one long and smooth d1 seta. Setae dp and d2 absent. Terminal segment with two short and one long setae (h1–3). Terminal segment rectangular.

Rake-like organ ( Fig. 21E ): Thin, with very short teeth.

Uropod ( Fig. 21F ): with short ramus, one anterior claw and very short seta. Posterior claw absent. Caudal attachment short.

Zenker’s organ ( Fig. 22A ): with five rows (3 + 2) of spines.

Hemipenis ( Fig. 22B ): Lateral lobe subtriangular, medial lobe rounded.

Female description: Carapace shape ( Fig. 19C ) and size similar to male. A2 ( Fig. 22C ) with long claws, G1 and G3 claws similar in size, G2 and GM setae half as long as G1, y3 seta-like. z1 and z2 setae very short, about size of terminal segment. T1 ( Fig. 22D ) with one a seta and three unequally smooth long apical setae with lengths: h2>h1>h3. b, c and d setae not apparent. Genital organ simple, rounded ( Fig. 22E ). All other parts similar to male.

Accompanying ostracod species. See Appendix 2.

Differential diagnosis. Carapace surface with longitudinal striations, A1 without Wouters and Rome organs. A2 with unequally long z1 and z2 setae and G1 claw. T1 without vibratory plate, slightly asymmetrical in male. T2 five-segmented. T3 five-segmented, with 2 short and 1 long claw-like setae. Setae e, f and g absent in T2 and T3. Md-palp without beta seta. Mx1 with two smooth bristles on third endite. Hemipenis with a well-developed ms, ls subtriangular. Zenker’s organ with three medial and two apical rows of spines.

Remarks: Gupta (1989) described the second species of the genus, I. biharensis , from a well in Belan Bazar ( India) based on one female and a broken carapace. Karanovic & Ranga Reddy (2008) considered I. biharensis as a nomen nudum because the species description was incomplete. Thus, including the new species, three recognized species can be listed under the genus Indocandona . Table 3 provides comparison among the species, but a key is also provided:

Key to the species of the genus Indocandona

1. Carapace surface smooth............................................... I. nagarjuna Karanovic & Ranga Reddy - Carapace surface ornamented with long striations........................................................... 2 2. t2–3 bristles on A2 ending with bulbs..................................................... I. krishnakanti Gupta - t2–3 bristles on A2 claw-like, without bulbs.............................................. I. rusti n. sp. this study

Ecology: Indocandona rusti n. sp. is the third species of the genus Indocandona and the first record outside of India. The type species I. krishnakanti was first collected from a well in Bihar region by Gupta (1984) while the second species I. nagarjuna was reported from a freshwater bore-well on the campus of Nagarjuna University, Nagarjunanagar, India by Karanovic & Ranga Reddy (2008). Unlike those species, Indocandona rusti n. sp. was collected from the hyporheic zone of Independence Creek, in the middle of the wetted channel, where water temperature was 22.9°C, dissolved oxygen was 8.48 mg /L, specific conductance was 1233 µS/cm, and pH was 7.54. It occurs with a diversity of other stygobionts, including Eremidrilus worms, the mites Arrenurus, Brachypodopsis, Chappuisides, Lethaxonella, Meramecia and Uchidastygacarus , the amphipods P. cf. americana and S. hershleri and the isopod L. cf. cocytus .

Figures

FIGURE 19. Indocandona rusti n. sp. Male: (A) RV and (B) LV external view, (D) RV internal view (note damaged ventral side), (E) dorsal view, (F) normal pores with setae of LV posterior end, external view. Female: (C) LV external view. Scale bar: 200 µm for A–E, 100 µm for F.

FIGURE 20. Indocandona rusti n. sp. Male. (A) A1, (B) Distal part of A2, (C) Md, (D) Mx1. Scale bar: 20 µm.

FIGURE 21. Indocandona rusti n. sp. Male. (A) Left clasping organ, (B) Right clasping organ, (C) T2, (D) T3, (E) Rake-like organ, (F) Ur. Scale bar: 20 µm.

FIGURE 22. Indocandona rusti n. sp. (A) Zenker’s organ of male, (B) Hemipenis of male, (C) A2 of female, (D) T1 of female, (E) Genital organ of female. Scale bar: 20 µm.