Ozestheria richteri, 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 : 121-124

Ozestheria richteri sp. nov.

urn:lsid:zoobank.org:act:35804CD8-1540-44C0-BB7D-F55A92D44692

Fig. 38

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

Diagnosis

Ozestheria richteri sp. nov. is characterized by a short condyle with a hump at its base and a mediumwide occipital notch; a rounded ventral carapace margin; carapace ornamentation dorsally on carapace smooth or with irregular depression, from mid-carapace with granular or nodulous intermittent lirae; male rostrum with convex anterior margin, apex strongly rounded with right angle, ventral margin straight or with slightly convex hump; female rostrum anterior margin convex, apex strongly rounded, ventral margin convex with anterior notch; 9–11 (male) or 8–12 (female) antenna I lobes reaching to antenna II flagellomeres IV–V (male) or IV–V (female); 8–9 (male) or 9 (female) antenna II flagellomeres; 19 complete thorax segments; 10–17 large spines, varying in shape between conical and elongate and aciculate, unequal in size; 0–1 furcal setae.

Differential diagnosis

Ozestheria richteri sp. nov. can be differentiated from all other species by the shape of the condyle, rostrum and carapace ornamentation. It is the only species with a short condyle and wide occipital notch, which has a well-defined hump at the condyle base (this is usually only present in species with a longer condyle) and has fewer furcal setae (0–1) than most other species. The condyle is uniquely shaped by being short, but distally pointed. The broad male rostrum and nodular carapace ornamentation (present on growth bands of later ontogenetic stages) are shared only with O. pellucida and to a lesser degree O. rufa and no other short-condyled species. Ozestheria pellucida differs from O. richteri by the condyle shape, the lighter and pellucid carapace and the number of furcal setae (14 vs 0–1), and by the lack of liral ornamentation (well visible posteriorly on the carapace of O. richteri ). Ozestheria rufa differs from O. richteri by the pointed, drawn-out rostral apex, the number of antenna I lobes (16–19 vs 8–12), the number of complete thorax segments (23–24 vs 19) and the number of furcal setae (6–15 vs 0–1).

Etymology

The species is named in honor of the German zoologist Stefan Richter. Without Stefan’s contribution and support all the newly described species of Ozestheria would not have been discovered. He supervised and planned MS’ PhD thesis, which lay the foundation for this publication, participated in collecting specimens and started MS’ interest in these fascinating animals.

Type material

Holotype

AUSTRALIA – Western Australia • ♂; Paynes Find, Bullamanya Rock , pool 5; 29°09′50.9″ S, 117°39′40.4″ E; 20 Aug. 2011, B.V. Timms leg.; GenBank no: KJ705759 ( COI); AM P.91531.

Paratypes

AUSTRALIA – Western Australia • 2 ♂♂, 1 ♀; same data as for holotype; GenBank nos: KJ705756 to KJ705758 ( COI); AM P.91528 to P.91530 • 1 ♀; same data as for holotype; GenBank no: KJ705755 ( COI); NHMW-ZOO-CR-28480 .

Type locality

Western Australia, Paynes Find, Bullamanya Rock, pool 5, 29°09′50.9″ S, 117°39′40.4″ E.

Description

Males

CARAPACE ( Fig. 38a, c–d). Length 4.8–5.1 mm (HT: 5.1 mm), height 2.9–3.1 mm (HT: 3.1 mm). Coloration dorsally dark brown to nearly black (~⅓–⅔ of carapace) with roundish dark area below umbo, fading into yellowish-brown ventrally. 15–17 growth lines, 13 widely spaced and 2–4 crowded.

CARAPACE SHAPE. Dorsal margin straight, dorso-posterior corner rounded. Posterior margin widely rounded, supracurvate (b/H 0.39–0.44, HT: 0.44). Ventral margin widely rounded. Umbo position anterior to submedian (Cr/L 0.23–0.26, HT: 0.26).

CARAPACE ORNAMENTATION ( Fig. 38e–g). Larval valve and following growth bands smooth, following growth bands appear smooth, partly with irregular depressions or very anastomosing lirae. From about mid carapace, with shallow, inconspicuous, subparallel, anastomosing lirae forming ventrally on growth bands (nodular under SEM, highly nodular with incipient crowding in the ventral and anterior part of the carapace). Concentric ridges shallow. Setae spiniform, preserved along carapace margin (under SEM setal pores along all growth lines, dorsally and medially on carapace with two alternating rows of setal pores on early concentric ridges, ventrally a single row).

HEAD ( Fig. 38h). Condyle short, slightly elongate and pointed distally; occipital notch medium wide. Condyle with well-developed anterobasal hump. Margin between condyle and ocular tubercle weakly concave. Ocular tubercle well developed, forming obtuse angle with rostrum (close to 90°). Anterior margin of rostrum convex, protruding anteriorly. Ventral margin of rostrum nearly straight or with slightly convex hump mid-length (HT: with hump) with notch close to apex, apex broadly rounded, acute. Naupliar eye triangular. Antenna I with 9–11 (HT: 11) lobes, reaching to antenna II flagellomeres IV–V (HT: IV). Antenna II with 8–9 (HT: 9) flagellomeres.

THORAX. 20 segments, 19 thoracopod-bearing and one posterior limbless segment not reaching dorsal margin. Dorsal armature well developed in last eight segments, spines thin and elongated, central spines stronger and broader in posterior segments.

THORACOPOD III (only P.91531; Fig. 38l). 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 than endopod; dorsal extension wide, narrowing distally, overreaching epipod. Epipod long, cylindric.

TELSON ( Fig. 38j–k). 8–12 (HT: 12) spines. First (anterior) spine enlarged. Spines of highly variable size and spacing (mostly widely spaced, space increases posteriorly), varying in shape between broad, conical and elongate, slender, aciculate. Several larger spines interspersed among much smaller spines. Dorsal margin nearly straight, posteriorly slightly concavely curved. Right terminal claw more strongly curved than left.

FURCA ( Fig. 38j–k). Proximally with dorsomedial longitudinal row of 0–1 seta (HT: 1) setae, row ending distally in a single conical spine. Distal part ½ of furca length, with numerous small denticles.

Females

Very similar to males. Carapace ( Fig. 38b) length 3.9–4.0 mm, height 2.5–2.6 mm. 16–17 growth lines, of these 12–14 evenly spaced and 3–4 crowded; Cr/L 0.23–0.24 and b/H 0.47–0.48. Ocular tubercle and rostrum form acute angle (~20–80°); rostrum anterior margin convex; apex widely rounded, rectangular (not drawn out), ventral margin convex with anterior notch ( Fig. 38i). Antenna I with 8–12 indistinct lobes, reaching to antenna II flagellomeres IV–V. Antenna II with nine flagellomeres. Telson 16–17 spines, their shape, size and spacing as in males. Furca bearing 0–1 seta.

Distribution ( Fig. 38m)

Currently known only from its type locality in western Western Australia.

Remarks

The carapace shape of Ozestheria richteri sp. nov. ( Fig. 5) is distinct from that of most other species and overlaps partly with those of O. rubra , O. henryae sp. nov., O. berneyi and O. gemina sp. nov.