Ozestheria mariae ( Olesen & Timms, 2005 )

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 : 85-88

Ozestheria mariae ( Olesen & Timms, 2005)

Fig. 27

Caenestheriella mariae Olesen & Timms, 2005: 1–8 , figs 1–4

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

Ozestheria mariae – Schwentner et al. 2020: figs 1–2. — Rogers 2020: 24.

Diagnosis

Ozestheria mariae is characterized by a long condyle and a narrow occipital notch; carapace ornamentation with shallow, anastomosing, inconspicuous lirae in early ontogenetic stages, which become more pronounced and nodular in progressing growth bands (visible only under high magnification); a lack of punctae on growth bands of early ontogenetic stages; angle between ocular tubercle and rostrum rectangular; male rostrum with convex anterior margin, apex strongly rounded with ~90° angle, ventral margin with anterior notch, otherwise straight; female rostrum anterior margin straight, apex weakly rounded, rectangular (not drawn out), ventral margin straight to weakly concave; 10–11 (male) or 8 (female) antenna I lobes reaching to antenna II flagellomeres V–VIII (male) or II (female); 10 (male and female) antenna II flagellomeres; 19–20 complete thorax segments; 8–14 telsonic spines, widely and irregularly spaced, subequal in length with 1–2 larger spines interspersed, posterior spines slightly increasing in size; 2 furcal setae.

Differential diagnosis

Ozestheria mariae can be differentiated from other species of Ozestheria with a long condyle by the combination of the ornamentation (shallow, inconspicuous lirae; lacking punctae), the rectangular angle between ocular tubercle and rostrum, the shape of the male and female rostrum, the number of complete thorax segments (19–20), the low number of antennule lobes and antenna flagellomeres (~10) and the number, size and distribution of telsonic spines. Morphologically most similar are O. carnegiensis sp. nov., O. quinlanae sp. nov. and O. weeksi sp. nov. (but punctae in carapace ornamentation; more antennule lobes and antenna flagellomeres), and O. barcaldinensis sp. nov. (but punctae in carapace ornamentation, lirae reticulating and pit-like; obtuse angle between ocular tubercle and rostrum). Ozestheria mariae yields a similar ornamental pattern as O. setifera sp. nov. with intermittent, nodular lirae on the lower part of mid-carapace growth bands while the upper part is smooth to granular, but differs in having fewer setae on the carapace, overall carapace shape and the number of telsonic spines.

Type material

Holotype (not examined) AUSTRALIA – Western Australia • ♂; Gnamma pool on Bushfire Rock, near Hyden ; 32°36 ″ S, 119°20 ″ E; Jun. 2003; B.V. Timms leg.; WAM C34418 .

Paratypes (not examined) AUSTRALIA – Western Australia • 1 ♀; same data as for holotype; ZMUC CRU-4854 • 1 spec.; same data as for holotype; AM P.68560 .

Paratypes AUSTRALIA – Western Australia • 3 ♂♂, 2 ♀♀; same data as for holotype; WAM C34420 .

Type locality

Western Australia, Gnamma pool on Bushfire Rock, near Hyden, 32°36′ S, 119°20′ E.

Description

Males (information on holotype taken from Olesen & Timms 2005)

CARAPACE ( Fig. 27a, c–d ). Length 4.6–5.3 mm (HT: 5.2 mm), height 2.9–3.2 mm. Coloration larval valve and several following growth bands yellowish to dark brown colored, remainder whitish and semitranslucent. 21–28 growth lines (HT: ~16), 18–23 widely spaced and 3–9 crowded.

CARAPACE SHAPE. Dorsal margin straight, dorso-posterior corner rounded. Posterior margin broadly rounded, suboval, supracurvate to equicurvate (b/H 0.43–0.50). Ventral margin broadly rounded. Umbo position submedian (Cr/L 0.28–0.29).

CARAPACE ORNAMENTATION ( Fig. 27e–h ). Larval valve granular (appears smooth under SEM due to missing outer cuticle layers). Following growth bands with shallow, inconspicuous, anastomosing lirae forming ventrally on growth bands, these become slightly more pronounced on later and crowded growth bands; under SEM the lirae dissolve into a series of small, nodular radial structures, rather than continuous lirae. Crowded growth bands with sub-parallel lirae (under SEM also short and nodular). Lirae mostly terminate ventrally in comparatively large nodules on concentric ridge (best seen under SEM). Concentric ridges slightly raised. Setae thick and mid-long, preserved in large numbers in a single row along most growth lines (setal pores in two irregular rows mid-dorsally and one row along growth lines of later ontogenetic stages under SEM).

HEAD ( Fig. 27i ). Condyle long, distally acute; occipital notch narrow. Condyle with anterobasal hump. Margin between condyle and ocular tubercle weakly to strongly concave. Ocular tubercle well developed (in some individuals with small tubercle on ocular tubercle), forming nearly rectangular angle with rostrum. Anterior margin of rostrum convex. Apex strongly rounded with ~90° angle. Ventral margin of rostrum with anterior notch, otherwise straight. Naupliar eye small roundish to sub-triangular. Antenna I long with 10–11 lobes (HT: ~11), reaching to antenna II flagellomeres V–VIII. Antenna II with 10 flagellomeres.

THORAX. 20 (HT: 19) segments, 19–20 thoracopod-bearing and none to one posterior limbless segment not reaching dorsal margin. Spines on dorsal extension relatively short and stout.

THORACOPOD III (only WAM C34418, based on Olesen & Timms 2005). Endite I short and curved dorsally. Endites II–V broad, decreasing in size. Endite V palp two-segmented, basal segment subequal in length to endopod. Exopod ventral extension shorter in extension than endopod, dorsal extension wide, narrowing distally, overreaching epipod. Epipod long, cylindric.

TELSON ( Fig. 27k ). 8–11 spines. First (anterior) spine enlarged. Most spines short, conical, subequal in length; one or two slightly larger spines interspersed; rather widely and irregularly spaced; posteriormost spines increasing in size, thin, aciculate. Dorsal margin straight. Right terminal claw more strongly curved than left.

FURCA ( Fig. 27k ). Proximally with dorsomedial longitudinal row of 4 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. 27b ) length 3.6–4.2 mm, height 2.3–2.7 mm; 24 growth lines, 19–20 widely spaced and 3–5 crowded (in one individual 12 wide growth lines are followed by 5 crowded and then another 7 wide growth lines of a secondary growth phase; ornamentation of secondary growth phase with subparallel lirae); Cr/L 0.28 and b/H 0.45–0.49. Margin between condyle and ocular tubercle straight to strongly concave ( Fig. 27j ). Anterior margin of rostrum straight; apex weakly rounded, rectangular, not drawn out; ventral margin straight to weakly convex. Antenna I with 8 small lobes, lobes smaller than in males; reaching to antenna II flagellomere II. Antenna II with 10 flagellomeres. 20 segments, all thoracopod-bearing. Telson with 14 dorsal spines; left and right terminal claws equally or right stronger curved. Furca with 2 setae.

Distribution ( Fig. 27l )

The species is known only from a few localities in southwestern Western Australia, all in small water bodies on rocky outcrops.

Remarks

Olesen & Timms (2005) assigned O. mariae to the genus Caenestheriella and distinguished it from the only other Australian species of Caenestheriella (now Ozestheria ) accepted at that time – O. packardi . However, all the characters suggested are in fact shared by several other of the herein newly described species of Ozestheria (e.g., the hump at the base of condyle or the well-developed ocular tubercle), which are thus not sufficient to distinguish O. mariae from other species of Ozestheria .

In the geometric morphometric analyses of the carapace shape ( Fig. 6 ), O. mariae is distinct from most other species and clusters with O. sivesae sp. nov., O. setifera sp. nov., O. marthae sp. nov., O. cancellata comb. nov., O. weeksi sp. nov., O. pilbarensis sp. nov., and O. gemina sp. nov. The mean shape of O. mariae is similar to that of O. setifera (54.3%), O. gemina (37.8%) and O. quinlanae sp. nov. (5.2%), which were associated with high typicality scores of 0.79, 0.77 and 0.84, respectively (Supp. file 2_4.8), but the ornamentation patterns of these species did not match that of O. mariae .

Figures

Fig. 27. Ozestheria mariae (Olesen & Timms, 2005), paratypes (WAM C34420).a–d. Carapace.a. Male. b. Female. c. Dorsal view (left valve only, male). d. Male, SEM. e–h. Carapace ornamentation (positions marked in d by rectangle), SEM. e. Larval valve and dorsal carapace. f. Mid-dorsal carapace. g. Midventral carapace. h. Ventral carapace. i–j. Head, antennae not shown. i. Male. j. Female. k. Telson, male. l. Distribution map (produced in ArcMap 10.7; see caption Fig. 7 for sources). Scale bars: a–d = 0.5 mm; e–h=0.1 mm; i–k= 0.2 mm.

Fig. 6. Morphometrics of long-condyled species. upper. Scores on PC1 and PC2 of Fourier shape coefficients of 497 outlines, including 480 new individuals and 17 historic type specimens, two of which are drawings of Ozestheria cancellata (Spencer & Hall, 1896) and O. packardi (Brady, 1886). The names used by Schwentner et al. (2015a) to identify genetically delimited species (e.g., A, B etc.; extended for the newly identified species, e.g., X2) are provided. New specimens are represented by convex hulls, type specimens and species documented by a single specimen (U, W, X7) by data points. lower. Mean shape of each species, calculated based on up to 67 individuals per species.