Ozestheria paralutraria, 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 : 105-108

Ozestheria paralutraria sp. nov.

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Fig. 33

Diagnosis

Ozestheria paralutraria sp. nov. is characterized by a short condyle and wide occipital notch; a straight ventral carapace margin; a supracurvate posterior margin (b/H 0.32–0.38); carapace ornamentation with large, well-developed polygonal reticulations, center of each polygon smooth or with granular secondary ornamentation (best seen under SEM); male rostrum with strongly convex anterior margin, apex rounded with right angle, ventral margin strongly concave, pointing apex downwards; female rostrum anterior margin weakly convex, apex pointed and drawn out into acute tip, ventral margin weakly concave; 15 (male) or 13–18 (female) antenna I lobes reaching to antenna II flagellomeres VI–VIII (male) or V–VI (female); 14–15 (male and female) antenna II flagellomeres; 23–24 complete thorax segments; 16–27 very small and irregularly spaced, conical spines; 12 furcal setae.

Differential diagnosis

Ozestheria paralutraria sp. nov. is most similar to O. lutraria from which it can be differentiated by it having fewer thoracic segments (24 vs 25–27 complete segments), more telsonic spines (16–18 in O. paralutraria , whereas O. lutraria rarely has more than 15), fewer and longer setae on the carapace (in a single row vs in two rows along each concentric ridge in O. lutraria ; best seen under SEM) and length of the carapace (up to 9 mm vs> 10 mm in O. lutraria ; n= 4 vs n= 73). Ozestheria paralutraria has a straight ventral carapace margin, which in combination with a short condyle is present only in O. lutraria , O. fuersichi sp. nov. and O. rufa . The carapace ornamentation of O. rufa features distinctly smaller reticulations in early growth bands and nodulous lirae in mid-carapace rather than the well-defined reticulations of O. paralutraria . Ozestheria fuersichi lacks the well-defined reticulation in mid-carapace. Ozestheria paralutraria can be further differentiated from most other species by the strongly supracurvate posterior carapace margin (b/H 0.32–0.38).

Etymology

The name is based on another morphologically similar species – O. lutraria . The Greek prefix ‘ para ’ (meaning ‘altered’ or ‘irregular’) hints at the great morphological similarity of the two species.

Type material

Holotype

AUSTRALIA – Western Australia • ♀; K.P.W floodout, 22 km N of Wittenoom ; 22°7′46.7″ S, 118°24′4.2″ E; 4 Aug. 2015; B.V. Timms leg.; GenBank no: PQ427013 ( COI); WAM C78013 .

Paratypes

AUSTRALIA – Western Australia • 1 ♂, 1 ♀; same data as for holotype; WAM C80216 , C80217 • 1 ♂; same data as for holotype; NHMW-ZOO-CR-28498 .

Type locality

Western Australia, K.P.W floodout, 22 km N of Wittenoom, 22°7′46.7″ S, 118°24′4.2″ E.

Description

Males

CARAPACE ( Fig. 33a, c). Length 8.9–9.9 mm, height 4.4–5.0 mm. Coloration light yellow-orange, crowded growth bands lighter. 24–27 growth lines, 15–20 widely spaced and 9–17 crowded.

CARAPACE SHAPE. Dorsal margin straight, distinct dorso-posterior corner. Posterior margin rounded, greatly extending posteriorly, supracurvate (b/H 0.36–0.38). Ventral margin straight. Umbo position anterior (Cr/L 0.21–0.24).

CARAPACE ORNAMENTATION (see also Fig. 33e–f). Larval valve and first few growth bands appear smooth (might be due to abrasion). All other non-crowded growth bands with medium to large reticulations. Reticulations form polygonal mesh across each growth band with each polygon usually being a pentagon, hexagon or heptagon. Under SEM (based on SEM of female carapace), polygon centers smooth or granular in late juvenile growth bands, without secondary reticulations. Ornamentation uniform across all non-crowded growth bands; reticulations become irregular and transition to broken lines on growth bands of incipient carapace crowding; crowded growth bands very narrow, without obvious ornamentation (under SEM, crowded growth bands with irregular, granular, lirae-like ornamentation). Concentric ridges raised. Setae short, thin and inconspicuous, in many individuals none visible; under SEM one row of setae and corresponding setal pores along all growth lines.

HEAD ( Fig. 33g). Condyle short, rounded; occipital notch wide. Condyle with anterobasal hump. Margin between condyle and ocular tubercle straight. Ocular tubercle well developed, forming obtuse (~120°) angle with rostrum. Anterior margin of rostrum strongly convex. Apex rounded with nearly rectangular angle. Ventral margin of rostrum deeply concave, pointing apex downwards. Naupliar eye small, roundish. Antenna I long with 15 lobes, reaching to antenna II flagellomeres VI–VIII. Antenna II with 14–15 flagellomeres.

THORAX. 25 segments, 24 thoracopod-bearing and one posterior limbless segment not reaching dorsal margin. Only few segments with spine-bearing dorsal extensions, posterior segments lacking spines.

THORACOPOD III (only NHMW-CR-28498; Fig. 33k). 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 slightly shorter in extension to endopod, dorsal extension wide, narrowing distally, overreaching epipod. Epipod long, cylindric.

TELSON ( Fig. 33i). 16–18 spines. First (anterior) spine enlarged. All spines conical; spines small or tiny, irregular in size and spacing. Dorsal margin weakly concave. Right terminal claw more strongly curved than left.

FURCA ( Fig. 33i). Broken off in all studied males.

Females

Overall appearance as in males. Carapace ( Fig. 33b, d) length 8.0– 8.9 mm (HT: 8.9 mm), height 4.1– 4.2 mm (HT: 4.2 mm); 17–18 (HT: 17) growth lines, 14–15 (HT: 14) widely spaced and 2–4 (HT: 3) crowded; Cr/L0.21–0.24 (HT: 0.24) and b/H 0.32–0.35 (HT: 0.35). Angle between ocular tubercle and rostrum obtuse (~160°) to straight ( Fig. 33h). Anterior margin of rostrum weakly convex, apex drawn out into acute, pointed tip; ventral margin weakly concave. Antenna I with 13–18 small lobes (HT: 18), lobes smaller than in males; reaching to antenna II flagellomeres V–VI (HT: VI). Antenna II with 14–15 flagellomeres (HT: 14). 24–25 (HT: 24) segments, 23 thoracopod-bearing and one to two (HT: 1) posterior limbless segments not reaching dorsal margin. Telson with 16–27 (HT: 27) dorsal spines (HT: posteriormost spines tiny); left and right terminal claws equally curved ( Fig. 33j). Furca with 12 setae, followed by single elongate spine; distal part ⅓–½ (HT: 1/3) of furcal length, with numerous small denticles.

Distribution ( Fig. 33l)

Ozestheria paralutraria sp. nov. is known only from a single locality in northwestern Western Australia.

Remarks

A female was selected as the holotype, because the telson and furca of each male were damaged. The carapace shape of Ozestheria paralutraria sp. nov. ( Fig. 5) is distinct from that of most other species and overlaps partly with O. lutraria .