Ozestheria sivesae, Schwentner & Hethke, 2025

Schwentner, Martin & Hethke, Manja, 2025, Revision of the Australian Ozestheria Schwentner & Richter, 2015 (Crustacea: Branchiopoda: Spinicaudata) fauna, with the descriptions of 27 new species, European Journal of Taxonomy 992, pp. 1-172 : 147-150

Ozestheria sivesae sp. nov.

urn:lsid:zoobank.org:act:E86EC450-37BD-41D3-B398-2AC8A2F38177

Fig. 46

Ozestheria sp. I – Schwentner et al. 2015a: figs 2, 6; 2020: figs 1–2.

Diagnosis

Ozestheria sivesae sp. nov. is characterized by a long condyle and a narrow occipital notch; a broadly rounded ventral carapace margin; carapace ornamentation punctate dorsally on carapace, from mid-dorsal carapace smooth band dorsally within growth bands followed by punctae and shallow lirae (smooth bands become more pronounced in following growth bands); male rostrum with straight anterior margin, apex rounded with acute angle (close to rectangular), ventral margin concave to nearly straight; female rostrum anterior margin weakly concave, apex weakly drawn out (not into acutely pointed tip) with acute angle (nearly rectangular), ventral margin weakly convex to straight; 12–16 (male) or 11–14 (female) antenna I lobes reaching to antenna II flagellomeres V–VI (male) or IV–V (female); 12–14 (male) or 10–13 (female) antenna II flagellomeres; 19–21 complete thorax segments; 19–27 telsonic spines of varying size, larger and smaller spines almost alternating, anterior spines conical, posterior spines thinner, elongate, aciculate; 8–12 furcal setae.

Differential diagnosis

Ozestheria sivesae sp. nov. can be easily differentiated from most other Australian species of Ozestheria by the characteristic carapace ornamentation with the smooth band dorsally within growth bands. Three other species have (partially) smooth growth bands: Ozestheria jiangi sp. nov., Ozestheria setifera sp. nov. and Ozestheria echidna sp. nov. Neither O. jiangi nor O. echidna have punctae ventrally of the smooth carapace ornamentation. Ozestheria setifera has nodular, more irregular lirae. Furthermore, O. setifera and O. echidna have dense, conspicuous setation along all growth bands (setae mostly broken off in O. sivesae ). In O. setifera setal pores on concentric ridges are arranged in 2–3 rows. In O. echidna only short lirae are present and these only mid-dorsally on the carapace (ventrally on carapace growth bands completely smooth) and in O. jiangi dorsal growth bands are largely smooth (only short ventral lirae, which become longer in later growth bands, from about mid-dorsal carapace). Ozestheria sivesae differs from these and most other species also in the telsonic spination with the very variably sized spines.

Etymology

The species is named in honor of Claire Sives, who has worked on the ecology of the large branchiopod fauna on and around Bloodwood Station, New South Wales, and who took part in collecting some of the specimens studied here, including the species named after her.

Type material

Holotype

AUSTRALIA – New South Wales • ♂; Bloodwood Station, Freshwater Lake , 29°29′14.7″ S, 144°49′59.0″ E; 19 Feb. 2010, M. Schwentner, C. Sieves and B.V. Timms leg.; GenBank no: KJ705775 ( COI); AM P.91547.

Paratypes

AUSTRALIA – New South Wales • 2 ♀♀; same data as for holotype; GenBank nos: KJ705776, KJ705777 ( COI); AM P.91548, P.91549 • 1 ♂; same data as for holotype; GenBank no: KJ705774 ; NHMW-ZOO-CR-28482 .

Additional material (not examined)

AUSTRALIA – Queensland • 1 juv.; Rockwell Station, Coolibah swamp; 28°54′03.2″ S, 144°59′22.6″ E; 1 Apr. 2009; M. Schwentner and B.V. Timms leg.; AM P. 91545 .

Type locality

New South Wales, Bloodwood Station, Freshwater Lake, 29°29′14.7″ S, 144°49′59.0″ E.

Description

Males

CARAPACE ( Fig. 46a, c–d). Length 3.9–4.0 mm (HT: 4.0 mm), height 2.4–2.5 mm (HT: 2.5 mm). Coloration lightly yellowish-brown. 20–22 (HT: 22) growth lines, 16–20 evenly spaced, and 0–6 crowded.

CARAPACE SHAPE. Dorsal margin straight, rounded dorso-posterior corner. Posterior margin broadly rounded, suboval, equicurvate (b/H 0.47–0.48, HT: 0.47). Ventral margin broadly rounded. Umbo position anterior (Cr/L 0.23–0.24, HT: 0.23).

CARAPACE ORNAMENTATION ( Fig. 46e–h). Larval valve and following growth bands finely reticulate to punctate. From about mid-dorsal carapace, unordered, shallow and short lirae appearing between punctae ventrally within growth bands, dorsal part of growth bands smooth; the dorsally smooth band becomes more pronounced in subsequent growth bands. Crowded growth bands too closely set to see ornamentation. Concentric ridges slightly raised, broad, with dorsal row of minute nodules in moniliform row ventrally on the carapace (visible under SEM). Setae filiform, preferentially preserved along the outer margin of the carapace. Setal pores in single row along all growth lines.

HEAD ( Fig. 46i). Condyle long, distally acute; occipital notch narrow. Condyle with anterobasal hump. Margin between condyle and ocular tubercle straight or weakly concave. Ocular tubercle weakly developed, forming widely obtuse angle with rostrum (close to 180°). Anterior margin of rostrum straight. Ventral margin of rostrum concave to nearly straight; apex extending well ventrally, broadly rounded, acute (close to 90°). Naupliar eye elongated, sub-rectangular. Antenna I with 12–16 (HT: 16) lobes, reaching to antenna II flagellomeres V–VI (HT: VI). Antenna II with 12–14 flagellomeres (HT: 14).

THORAX. 20–21(HT:21)segments, 19–20 (HT: 20) thoracopod-bearing and one posterior limbless segment not reaching dorsal margin. Last thirteen thoracopod-bearing segments with dorsal extensions bearing spines. Dorsal extensions increasing in size posteriorly over successive segments, well developed in last nine segments. Spines thin and elongated, central spines stronger and broader in posterior segments. The holotype (P.91547) with a single spine situated between the last clearly demarcated segment and the telson on the left side of the body (this appears to be a deformation, maybe due to a not properly developed segment; not present in the other individuals).

THORACOPOD III (only P.91547; Fig. 46k). Endite I short and curved dorsally. Endites II–V broad, decreasing in size. Endite V palp two-segmented, basal segment shorter than endopod. Exopod ventral extension shorter in extension to endopod, dorsal extension wide, narrowing distally, overreaching epipod. Epipod long, cylindric.

TELSON ( Fig. 46l–m). 21–27 spines (HT: 21). First (anterior) spine enlarged. Spines of varying size, smaller and slightly enlarged spines more-or-less alternating; anterior spines conical, posterior spines thinner, elongate, aciculate. Dorsal margin nearly straight. Right terminal claw more strongly curved than left.

FURCA ( Fig. 46l–m). Proximally with dorsomedial longitudinal row of 12 setae, row ending distally in a single conical spine. Distal part ⅔ of furca length, with numerous small denticles.

Females

Overall appearance as in males. Carapace ( Fig. 46b) length 3.6–3.9 mm, height 2.2–2.5 mm; 17–18 growth lines, all of these widely spaced, Cr/L 0.25 and b/H 0.46–0.49. Anterior margin of rostrum weakly concave; apex with acute angle (close to 90°), weakly drawn out; ventral margin weakly convex to straight; overall rostrum shape trapezoidal ( Fig. 46j). Naupliar eye elongated, sub-rectangular to sub-triangular. Antenna I with 11–14 small lobes, lobes smaller than in males; reaching to antenna II flagellomeres IV–V. Antenna II with 10–13 flagellomeres. 21 segments, 20–21 thoracopod-bearing and none to one posterior limbless segment not reaching dorsal margin. Telson with 19–21 dorsal spines; left and right terminal claws equally curved. Furca with 8 setae.

Distribution ( Fig. 46n)

Currently known only from two localities in the catchment of the Paroo River in eastern Australia at the border between New South Wales and Queensland.

Remarks

Because only few specimens were available, the morphological variability of the species is not well characterized. The carapace shape of Ozestheria sivesae sp. nov. ( Fig. 6) is distinct from that of most other species and overlaps fully with those of O. cancellata comb. nov., O. weeksi sp. nov., O. pilbarensis sp. nov. and partly with O. timmsi sp. nov., O. setifera sp. nov., O. gemina sp. nov., O. marthae sp. nov., and O. selmae sp. nov. (marginally).