Ozestheria timmsi, 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 : 150-153

Ozestheria timmsi sp. nov.

urn:lsid:zoobank.org:act:F9FC30F8-FA27-44BB-9E09-4DB92E842F6E

Fig. 47

Ozestheria sp. H 1 – Schwentner et al. 2015a: figs 2, 6.

Ozestheria sp. H – Schwentner et al. 2020: figs 1–2.

Diagnosis

Ozestheria timmsi sp. nov. is characterized by an elongate, but strongly rounded condyle and a narrow occipital notch; carapace ornamentation dominated by large, pit-like punctae, in later growth bands inconspicuous lirae forming between punctae (lirae mainly posteriorly and ventrally on carapace); male rostrum with strongly convex anterior margin, apex rounded, nearly rectangular (~90–100°), ventral margin convexly curved or straight; female rostrum with weakly convex (nearly straight) anterior margin, apex rectangular and usually rounded, ventral margin slightly convex or s-shaped; 11–14 (male) or 12–14 (female) antenna I lobes reaching to antenna II flagellomeres VII–X (male) or III–VI (female); 16–18 (male) or 15–22 (female) antenna II flagellomeres; 23–24 complete thorax segments; 17–31 telsonic spines, spines small with 3–4 larger spines interspersed, anteriorly broad, conical and posteriorly thin and aciculate; 6–10 furcal setae.

Differential diagnosis

Ozestheria timmsi sp. nov. can be differentiated from all other species of Ozestheria by the combination of the carapace ornamentation (dominated by pit-like punctae), the carapace shape, size and coloration (generally dark) as well as the rostrum shape and telson spination. Species with similar carapace ornamentation are O. frederikeae sp. nov. and O. carnegiensis sp. nov., which both have shorter carapace lengths (reaching only up to 7 mm) and fewer complete thorax segments (≤ 21 vs ≥ 23). Furthermore, O. carnegiensis has fewer antenna flagellomeres (≤ 14 vs ≥ 15) and fewer telsonic spines (11–20 vs 17– 31). Female O. frederikeae have an undulating anterior rostrum margin and fewer antenna flagellomeres (14–17 vs 15–22).

Etymology

The species is named in honor of Brian V. Timms. Brian has worked extensively on the ecology and taxonomy of Australia’s large branchiopods and his work has transformed our understanding of their diversity. He also collected the vast majority of the material studied herein; without his relentless efforts and dedication this study would not have been possible.

Type material

Holotype

AUSTRALIA – Queensland • ♂; Lake Louisa ;, 19°53′46.7″ S, 144°15′57.4″ E; 7 Apr. 2009; M. Schwentner and B.V. Timms leg.; GenBank no: KJ705772 ( COI); AM P.91544.

Paratype

AUSTRALIA – Queensland • 1 ♀; same data as for holotype; GenBank no: KJ705761 ( COI); AM P.91533 • 3 ♂♂, 7 ♀♀; same data as for holotype; 12 Apr. 2018; NHMW-ZOO-CR-26637 .

Other material examined

AUSTRALIA – Queensland • 2 ♂♂, 2 ♀♀; Pelican Lake ; 19°53′46.7″ S, 144°15′57.4″ E; 24 Jun. 2020; B.V. Timms leg.; NHMW-ZOO-CR-26638, NHMW-ZOO-CR-26639 • 1 ♂; Salt Bore Lake ; 19°51′22.3″ S, 144°16′08.5″ E; 6 Apr. 2009; M. Schwentner and B.V. Timms leg.; AM P.91532 • 4 ♀♀; Salt Bore Lake ; 19°51′22.3″ S, 144°16′08.5″ E; 24 Jun. 2020; B.V. Timms leg.; NHMW-ZOO- CR-26640, NHMW-ZOO-CR-26641 .

Type locality

Queensland. Lake Louisa, 19°53′46.7″ S, 144°15′57.4″ E.

Description

Males CARAPACE ( Fig. 47a, c–e). Length 8.3–9.6 mm (HT: 9.6 mm), height 5.1–5.8 mm (HT: 5.8 mm). Coloration light to dark reddish-brown or nearly black, outer margin lighter. 36 –50 (HT: 50) growth lines, of these 28–35 widely spaced (HT: 35) and 4–15 (HT: 15) crowded.

CARAPACE SHAPE. Dorsal margin straight, dorso-posterior corner rounded. Posterior margin widely oval, equicurvate (b/H 0.47–0.50, HT: 0.48). Ventral margin rounded, strongly and uniformly curved. Umbo position anterior to submedian (Cr/L 0.22–0.27, HT: 0.26).

CARAPACE ORNAMENTATION ( Fig. 47f–i). All growth bands densely punctate (larval valve and first few growth bands appear to be smooth in several individuals, but that is probably due to abrasion), punctae large and pit-like or net-like. From about mid-carapace, inconspicuous lirae forming between punctae ventrally on growth bands, lirae stronger defined ventrally and posteriorly on the carapace. Crowded growth bands with less conspicuous punctae, space between punctae slightly raised, lirae-like (especially posteriorly). Concentric ridges slightly raised and smooth. Setae filiform, preserved usually only on outer growth lines (under SEM all growth lines with single row of setal pores).

HEAD ( Fig. 47j). Condyle long, distally rounded; occipital notch narrow. Condyle with weakly developed anterobasal hump. Margin between condyle and ocular tubercle straight. Ocular tubercle weakly developed, forming obtuse to straight angle (~100–180°) angle with rostrum. Anterior margin of rostrum strongly convex. Ventral margin of rostrum convexly curved or straight, no anterior notch; apex rounded, nearly rectangular (~90–100°). Naupliar eye elongated, subrectangular to subtriangular with rounded edges. Antenna I long with 11–14 lobes (HT: 11), reaching to antenna II flagellomeres VII–IX (HT: VIII). Antenna II with 16–18 flagellomeres (HT: 18).

THORAX. 24–25 (HT: 25) segments, 23–24 (HT: 23) thoracopod-bearing and 1–2 (HT: one) posterior limbless segment not reaching dorsal margin. Dorsal armature increasing in size posteriorly over successive segments, central spines long and thin, laterally row of smaller spines. In posteriormost segments central spines stouter and shorter.

THORACOPOD III (only P.91533; Fig. 47n). Endite I short and curved dorsally. Endites II–V broad, decreasing in size. Endite V palp one-segmented. Exopod ventral extension subequal in extension to endopod, dorsal extension wide, narrowing distally, overreaching epipod. Epipod long, cylindric.

TELSON ( Fig. 47l–m). 17–29 spines (HT: 29). First (anterior) spine enlarged. Spines subequal in length, small and thin.Anterior spines conical, posterior spines becoming thinner and more drawn out (aciculate) and more densely spaced. 3–4 larger spines (~2 × in size) interspersed, one about half-length of telson. Dorsal margin straight to slightly concave. Right terminal claw more strongly curved than left.

FURCA ( Fig. 47l–m). Proximally with dorsomedial longitudinal row of 8–10 (HT: damaged) setae, row ending distally in a single conical spine. Distal part ⅔ of furcal length, with numerous small denticles.

Females

Overall appearance as in males. Carapace ( Fig. 47b) length 7.9–11.5 mm (mean: 8.7 mm), height 5.0– 7.6 mm (mean: 5.5 mm); 36–45 (41) growth lines, 23–25 (mean: 29) widely spaced and 5–20 (mean: 13) crowded; Cr/L 0.21–0.26 (mean: 0.24) and b/H 0.46–0.53 (mean: 0.50). Anterior margin of rostrum only weakly convex (nearly straight), apex more rectangular than in males but usually rounded. Ventral margin slightly convex or s-shaped. Angle between eye bulge and rostrum widely obtuse, nearly straight ( Fig. 47k). Antenna I short with 12–14 (mean: 13) small, well-defined lobes, lobes smaller than in males; reaching to antenna II flagellomeres III–VI (mean: IV). Antenna II with 15–22 flagellomeres (mean: 18). 24–25 (mean: 25) segments, 23–24 (mean: 24) thoracopod-bearing and one to two posterior limbless segments not reaching dorsal margin. Telson with 24–31 (mean: 27) dorsal spines; up to 3–5 larger spines interspersed. Furca with 6–10 setae.

Distribution ( Fig. 47o)

Ozestheria timmsi sp. nov. is known only from three localities in northern Queensland. It is the only species of Ozestheria recorded so close to the tropical climate zone.

Remarks

The carapace shape of Ozestheria timmsi sp. nov. ( Fig. 6) is distinct from that of most other species and overlaps with those of O. frederikeae sp. nov. (only marginally), O. sivesae sp. nov., O. setifera sp. nov., O. mariae , O. gemina sp. nov., O. jonnae sp. nov. (only marginally), O. marthae sp. nov., O. weeksi sp. nov., O. cancellata comb. nov., O. quinlanae sp. nov., O. pilbarensis sp. nov.