Ozestheria echidna, 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 : 47-50

Ozestheria echidna sp. nov.

urn:lsid:zoobank.org:act:09E54F6C-67ED-45FE-8DE6-6167AF1C7BA6

Fig. 16

Diagnosis

Ozestheria echidna sp. nov. is characterized by a long condyle and a narrow occipital notch; a broadly rounded ventral carapace margin; carapace ornamentation dorsally on carapace punctate, following growth bands smooth with short lirae ventrally within growth bands, lirae decrease in size in following growth bands (lirae absent in growth bands of later ontogenetic stages); carapace setae very long and thick, very densely arranged along most concentric ridges, giving the whole carapace a furry or pelt like appearance (setal pores of broken off setae clearly visible under stereo microscope); male rostrum with weakly convex anterior margin, apex rounded with right angle, ventral margin strongly concave, pointing apex downwards; female rostrum anterior margin straight or undulating, apex right angle (not rounded or drawn out into acute tip), ventral margin weakly concave or weakly convex; 9–14 (male) or 8–15 (female) antenna I lobes reaching to antenna II flagellomeres IV–IX (male) or IV–V (female); 11– 16 (male) or 12–16 (female) antenna II flagellomeres; 19–21 complete thorax segments; 31–44 telsonic spines, most spines aciculate, densely spaced, usually no larger spines interspersed, slightly increasing in length posteriorly; 4–11 furcal setae.

Differential diagnosis

Ozestheria echidna sp. nov. can be easily differentiated from most other Australian species of Ozestheria by the dense setation of the carapace (in most other species the majority of setae are broken off) and the characteristic carapace ornamentation with the extensive smooth band dorsally within growth bands and only short ventral lirae (lirae completely missing ventrally on carapace). Ozestheria setifera sp. nov. also has a dense carapace setation, but it has shorter and thinner setae, more pronounced and nodular lirae on the growth bands (which do not decrease in size ventrally on carapace) and fewer telsonic spines (18–31 vs 28–44). Ozestheria jiangi sp. nov. and O. sivesae sp. nov. also have smooth bands in their carapace ornamentation, but their growth bands contain prominent lirae (separated by punctae in O. sivesae ) ventrally on the carapace; they also lack the dense setation and differ in the shape of the male and female rostrum.

Etymology

The species is named after an iconic Australian animal, the echidna, due to the thick, dense and long spines on the species’ carapace. Echidna is a junior homonym that has become the common word for this species group; noun in apposition.

Type material

Holotype

AUSTRALIA – Western Australia • ♂; Chaddolinna Pool , 5 km E of Mulga Downs; 22°18′0.1″ S, 118°49′32.5″ E; 13 Mar. 2007; A.M. Pinder leg.; WAM C77994 .

Paratypes

AUSTRALIA – Western Australia • 1 ♂, 2 ♀♀; same data as for holotype; WAM C80241 to C80243 • 1 ♂; same data as for holotype; NHMW-ZOO-CR-29004 .

Other material examined

AUSTRALIA – Western Australia • 1 ♂, 1 ♀; 14 Mile Pool , 114 km N of Newman; 22°33′13″ S, 119°51′49.1″ E; 15 Mar. 2016; A.M. Pinder leg.; WAM C80233 , C80232 • 4 ♂♂, 1 ♀; Paradise Pool , 61 km SW of Pardoo; 20°22′35″ S, 119°25′21″ E; 13 Sep. 2014; B.V. Timms leg.; WAM C77992 , C80237 to C80240 • 4 ♂♂; Moorimoordinina Native Well , 118 km S of Nullagine; 22°30′48″ S, 119°46′15.4″ E; 10 Apr. 2008; A.M. Pinder leg.; WAM C77991 , C80244 to C80246 .

Type locality

Western Australia, Chaddolinna Pool, 5 km E of Mulga Downs, 22°18′0.1″ S, 118°49′32.5″ E.

Description

Males

CARAPACE ( Fig. 16a, c). Length 5.3–7.3 mm (HT: 6.7 mm, mean: 6.3 mm), height 3.1–4.5 mm (HT: 4.0 mm, mean: 3.8 mm). Coloration varying from light orange-brownish to light reddish-brown; outer margin lighter. 34–65 (HT: 43; mean: 48) growth lines, 12–58 (HT: 34; mean: 35) widely spaced and 3–37 (HT: 9; mean: 14) crowded; also, wide growth bands rather densely spaced.

CARAPACE SHAPE. Dorsal margin straight, dorso-posterior corner rounded. Posterior margin broadly rounded, suboval, equicurvate (b/H 0.48–0.52; HT: 0.49, mean: 0.51). Ventral margin broadly rounded. Umbo position submedian (Cr/L 0.25–0.30; HT: 0.26, mean: 0.27).

CARAPACE ORNAMENTATION (compare Fig. 16e–f). Larval valve and first few growth bands granular or punctate (puntate under SEM), in some individuals inconspicuous lirae forming between punctae. Following growth bands, dorsally within growth bands smooth, ventrally with short lirae; lirae decrease in extension in progressing growth bands (lirae become so reduced that they are only visible when terminating in the concentric ridge). Ornamentation usually concealed by setae. Crowded growth bands without apparent ornamentation. Concentric ridges shallow; under SEM smooth, appears serrated dorsally where the short lirae terminate. Setae very long and thick, very densely arranged along most concentric ridges, giving the whole carapace a furry or pelt-like appearance; setal pores of broken off setae clearly visible under stereo microscope; setal pores in irregular row along all growth lines.

HEAD ( Fig. 16i). Condyle long, distally rounded; occipital notch narrow. Condyle with anterobasal hump. Margin between condyle and ocular tubercle straight to weakly concave. Ocular tubercle weakly developed, forming obtuse (~150°) angle with rostrum. Anterior margin of rostrum weakly convex. Apex rounded with right angle. Ventral margin of rostrum strongly concave, pointing apex downwards. Naupliar eye subtriangular, varying in size. Antenna I long with 9–14 lobes (HT: 13; mean: 12), reaching to antenna II flagellomeres IV–IX (HT: IX; mean: VII). Antenna II with 11–16 flagellomeres (HT: 15; mean: 14).

THORAX. 20–21 (HT: 20, mean: 21) segments, 19–21 (HT: 19; mean: 20) thoracopod-bearing and one to no posterior limbless segment, not reaching dorsal margin. Most thoracopod-bearing segments with spine bearing dorsal extensions.

THORACOPOD III (only WAM C77994; Fig. 16l). Endite I short and curved dorsally. Endites II–V broad, decreasing in size. Endite V palp two-segmented, basal segment subequal to endopod. Exopod ventral extension subequal in extension to endopod, dorsal extension wide, narrowing distally, overreaching epipod. Epipod long, cylindric.

TELSON ( Fig. 16k). 28–44 spines (HT: 35; mean: 35). First (anterior) spine enlarged. Following spines slender, elongate; most anterior spines slightly conical, posterior spines aciculate; densely and regularly spaced, usually no larger spines interspersed; increasing in length posteriorly. Dorsal margin concave or undulating. Right terminal claw more strongly curved.

FURCA ( Fig. 16k). Proximally with dorsomedial longitudinal row of 4–11 (HT: 8, mean: 9) 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. 16b, d) length 5.6–6.7 mm, height 3.4–4.4 mm; 34–63 growth lines, 26–55 widely spaced and 3–8 crowded; Cr/L 0.26–0.29; b/H 0.48. Angle between head and rostrum nearly straight to obtuse (~150°) ( Fig. 16j). Rostrum frontal margin straight or slightly undulating. Apex with right angle, not rounded; ventral margin varying from weakly concave to weakly convex. Antenna I with 8–15 small lobes, lobes smaller than in males; reaching to antenna II flagellomeres IV–V. Antenna II with 12–16 flagellomeres. Telson with 31–38 dorsal spines; left and right terminal claws usually equally curved, sometimes right stronger curved. Furca with 8–14 setae.

Distribution ( Fig. 16m)

Ozestheria echidna sp. nov. is known from four geographically relatively close localities in northwestern Western Australia.

Remarks

The carapace shape of Ozestheria echidna sp. nov. ( Fig. 6) is distinct from that of most other species and overlaps partly with those of O. jiangi sp. nov., O. minor comb. nov., O. jonnae sp. nov., O. marthae sp. nov., O. selmae sp. nov., O. typica comb. nov., O. cancellata comb. nov., O. weeksi sp. nov., and O. glabra sp. nov.