Bradleystrandesia macula, 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 : 12-17

Bradleystrandesia macula n. sp.

( Figs 6–8 )

Type locality. Colorado River Basin , South Llano River at County Road 150 crossing, Kimble County , Texas, USA (Lat: 30.393 385, Long: -99.881913), Elevation ~ 541 m ASL .

Etymology. The species name refers to two spot-like loops on the ventral branch of uropodal attachment. In Latin, ‘macula’ means spot.

Material examined. Holotype: Female dissected in lactophenol solution with soft body parts slide mounted and sealed with translucent nail polish (no: OK-TX-SLl-161116 H2-1); valves kept in micropalaeontological slides (no: OK-TX-SLl-161116 H2-2). Collected from type locality on 11 November 2016 by Benjamin T. Hutchins and Aaron P. Swink.

Dissected paratypes. Five females from the type locality (no: OK-TX-SLl-161116 H2-3-7). Collected by Benjamin T. Hutchins and Aaron P. Swink.

Non-dissected paratypes: Many females and juveniles kept in 70% ethanol. Collected from type locality by Benjamin T. Hutchins and Aaron P. Swink.

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 (μ m). Female (n=5): LV: L=1110–1140 (mean = 1125), H=650–653 (mean = 652); RV: L=1073–1108 (mean = 1091), H=642–644 (mean = 643); W=530–533 (mean = 532).

Carapace ( Fig. 6 ) opaque white, subovate (length ca. 1.7x height) in lateral view, greatest height found in front of mid-length, anterior and posterior margins rounded, surface with small pits with spine like setae and normal pores, elliptical in dorsal view, both anterior and posterior margins rounded; LV overlapping RV anteriorly, ventrally and posteriorly; RV overlapping LV dorsally; hinge adont; LV internal view with inner list, groove absent, inner lamella calcified wide anteriorly, narrow posteriorly.

A1 ( Fig. 7A ): Seven-segmented. First segment without Wouters organ, two long smooth ventro-apical setae reaching to terminal segment and medium sized smooth dorso-subapical seta; second segment with smooth dorsoapical seta twice the length of the Rome organ; third segment with one long smooth dorso-apical seta extending to terminal segment and one short ventro-apical smooth seta about as long as terminal segment; fourth segment with two long dorsal setae, one sub-apical seta and one short ventro-apical seta; fifth segment with four long setae extending to tip of aesthetasc ya; penultimate segment with four long setae; terminal segment with three long setae, aesthetasc ya shorter than apical seta.

A2 ( Fig. 7B ): Four-segmented. First segment (protopodite) with two short basal setae and one long smooth postero-distal seta extending slightly past base of next segment. Second segment with one long and two short setae; aesthetasc Y strong, two-segmented, anteriorly plumose; posterior seta anteriorly plumose, reaching tip of terminal segment; natatory setae very short about one half length of penultimate segment; sixth seta longest. Penultimate segment undivided with two unequally long short antero-medial setae, one very short and three posterior t-setae (t1–3) unequal in length, t1 seta plumose (t1>t2>t3); setae z1–3 slightly shorter than G2 claw; three claws serrated, G1 and G3 claws equal in size, G2 claw short. Terminal segment with GM and Gm claws serrated, Gm claw one half length of GM. Aesthetasc y1–3 and g seta not seen.

Md-palp ( Fig. 7C ): Md-coxa well-developed with strong teeth. First segment with vibratory plate with six long plumose setae; three long setae (S1 and S2 and one smooth) equal in size, and alpha seta short and plumose; second segment dorsally with three unequally long apical setae; ventrally with three unequally long smooth setae and a short tube-like slightly plumose beta seta; penultimate segment with three smooth dorsal setae, gamma seta clawlike extending to tip of terminal claws; terminal segment with three smooth claws.

Mx1 ( Fig. 7D ): with three endites and Mx1-palp. Vibratory plate with 12–13 slightly setose setae. Third endite with two serrated bristles; first segment of Mx1 palp with three equally long outer setae and one very short inner seta; second segment rectangular with five claws.

T1 ( Fig. 8A ): Two short a setae, and almost equally long b and d setae present, c seta absent. Length of unequally long h-setae: h2>h1>h3. Vibratory plate with five setose setae.

T2 ( Fig. 8B ): five-segmented. Setae d1 and d2 similar in size, dp seta 3x longer than d1 and d2; e, f, and g setae smooth, lengths: f> e> g; penultimate segment short, h1 and h3 setae subequal; h2 seta claw-like.

T3 ( Fig. 8C ): four-segmented. First segment with three smooth and slim d-setae, lengths: d1> d2 ≈ dp. Second segment with along apical e seta reaching tip of next penultimate segment, about 2 x length of h seta, as in Fig. 8C . Penultimate segment undivided, with one lateral f seta. Terminal segment with pincer structure and reflexed subapical seta.

Rake-like organ ( Fig. 8D ): short with 6–7 strong teeth, base strong with short setae.

Uropod ( Fig. 8E ): caudal ramus slender ventral margin smooth, claws slim and weakly serrated, anterior claw (Ga) about one half length of ramus, length of posterior claw (Gp) about ¾ length of Ga, anterior seta (Sa) smooth and slightly shorter than Gp, posterior seta (Sp) plumose and very short and about ¼ length of Sa. Uropodal attach- ment with two spot-like loops near ventral branch (diagnostic character).

Genital organ ( Fig. 8G ): rounded without process.

Males: unknown.

Accompanying ostracod species. See Appendix 2.

Differential diagnosis. Bradleystrandesia macula n. sp. is distinguished from other species of the genus by the presence of spine-like setae on the carapace and differences in soft body parts including the length of aesthetasc ya, absence of c seta on T1, very short natatory setae on A2, a claw-like long beta seta on Md-palp, very short posterior (proximal) seta on uropod and two subrectangular or suboval Triebel loops on uropodal attachment.

Remarks. The absence of the c seta on the T1 is not known in any of the other 19 species of Bradleystrandesia , and the presence of two Triebel loops (one of which may not be complete) on the caudal ramus is not known in the family (if at all among ostracod species). Despite these differences, we still place the species in Bradleystrandesia because it most closely resembles other species of the genus.

Ecology: The species was found in the hyporheic zone at the littoral margin of the South Llano River. Water temperature was 18.9°C, dissolved oxygen was 7.00 mg/L, specific conductivity was 372 µS/cm, and pH was 7.85. In addition to the ostracod species listed in Appendix 2, B. macula n. sp. was collected alongside stygobiontic harpacticoid copepods and the stygobiontic mites Arrenurus and Stygomomonia . A number of epigean benthic invertebrates were also collected from the site ( Hutchins et al., 2020). The genus Bradleystrandesia includes about 19 species ( Meisch et al. 2019) reported from a variety aquatic habitats across a wide geographical distribution in Western and Eastern Asia, Europe, and North America. A comparison of all species is beyond the scope of this study, but one example is given to compare ecological characteristics. Bradleystrandesia weberi (Moniez) has been recorded from both natural and artificial aquatic habitats including roadside canals, pools, ponds, reservoirs, ricefields, wetlands, lakes, swamps, rivers, and natural springs ( Victor & Fernando 1981; Savatenalinton & Martens 2010). The species was collected from waters with pH ranging from 6.31 to 7.50 and temperature ranging from 26.7 to 34.1°C ( Savatenalinton & Martens 2010).

Figures

FIGURE 6. Bradleystrandesia macula n. sp. Female. (A) LV and (B) RV external view, (C) dorsal view, (D) ventral view, (E) LV internal view with anterior and posterior margins enlarged, (F) RV internal view with anterior and posterior margins enlarged, (G) muscle scars, (H) normal pore openings with seta. Scale bar: 100 µm for A–F, 50 µm for close-view of E and F, 10 µm for G and H.

FIGURE 7. Bradleystrandesia macula n. sp. (A) A1, (B) A2, (C) Md, (D) Mx1. Scale bar: 20 µm.

FIGURE 8. Bradleystrandesia macula n. sp. (A) T1, (B) T2, (C) T3, (D) Rake-like organ, (E) Ur and attachment, (F) Uropodal attachment enlarged, (G) Genital organ. Arrows point to double Triebel loop in E and F. Scale bar: 20 µm.