Caenestheriella mariae, Olesen, Jørgen & Timms, Brian, 2005

Olesen, Jørgen & Timms, Brian, 2005, caudata: Cyzicidae): a new clam shrimp from Western Australia, Zootaxa 824, pp. 1-8 : 2-7

Caenestheriella mariae sp. nov.

Material examined. All material from Western Australia. Holotype ( WAM C34418), male (5,2 mm), gnamma pool on Bushfire Rocks, near Hyden, 32° 26’S, 119° 20’E, 26 July 2003, B.V. Timms. Paratypes: ( WAM C34419, allotype), same data as holotype.: ( WAM C34420), same data as holotype; (AM P68560) same data as holotype; ( ZMUC CRU­ 4854), same data as holotype (includes specimens for SEM).

Other material. Paynes Find Rocks, near Paynes Find, 29° 10’S, 117° 40’E, 15 August 2003, WAM C34421; Remlap Homestead Rocks, near Beacon, 30° 20’S, 117°38’E, 15 August, 2003, WAM C34422; Wanarra Rocks, on Wanarra Station, 29° 31’S, 116° 48’E, 16 August, 2003, WAM C34423; Wardagga Rocks, on Ningham Station, 29° 23’S, 117° 30’E, 16 August 2003, WAM C34424, all collected B.V. Timms.

Description. Male (holotype) carapace 5.2 mm in length (description based on male holotype unless otherwise mentioned). Female (allotype) (ovigerous) carapace 4.8 mm in length. Carapace in both sexes oval, slightly highest anteriorly. Both sexes with relatively distinct umbo, broadest in female. Carapace with approximately 16 growth lines in male, about 18 in female. No distinct sculpturing present between growth lines except some granulations. The male head with three characteristic features: a ventral rostrum, a rounded eye lobe with the compound eye close to the margin, and a dorsal occipital condyle. The rostrum is pointed in lateral view with a pair of convex dorsal margins and a straight ventral margin. The occipital condyle, situated at the dorsal/posterior margin of the head, is bluntly pointed and drawn out posteriorly, and is rather narrow in anterior view ( Fig. 4 B). The rectangular dorsal organ is situated anterior to the occipital condyle ( Fig. 4 I). The occipital condyle, and the area anterior to it, is densely covered with small cuticular tubercles ( Fig. 4 I). The eye lobe and the rostrum together form a 90° angle. The female head differs slightly in shape from that of the male by having a more pointed incision between the eye lobe and the rostrum, and more rounded dorsal margins of the rostrum.

The antennule reaches to the third segment of the antennal rami and is subdivided into about 11 setose lobes at the anterior side. The antennal protopod is anteriorly subdivided into about 8 portions, each carrying a row of spines, plus a row of long, slender setae at the proximal­posterior margin. The anterior branch (endopod) has 10 segments, with 6–8 spines at the anterior margin of segments 1–6 and 3–6 long slender setae at the posterior margin. The posterior branch (exopod) has 11 segments with 1–6 spines at the anterior margin and 4–9 long slender setae at the posterior margin.

The trunk consists of 19 leg–bearing segments; the posterior legs being small. The posterior 13 or so trunk segments carry backwardly­pointing dorsal spines. The first and second pair of trunk legs are modified as claspers, in general very similar to each other. First clasper leg, right side: The medial margin of the basal and phyllopodous part of the limb is subdivided into three lobes (or endites): the proximal endite is curved and elongate and has a characteristic row of curved setae on one side, which points towards the food groove, and a cluster of slender setae on the other side; the proximal endite is followed distally by a long endite with a row of slender setae along its margin; distally, proximal to the clasper, is a short endite with marginal slender setae. On the lateral margin is attached a tubular, naked epipod and an exopod with a broad setose basal lobe and a slender setose distal lobe. Close to the attachment point on the exopod is a small setose lobe at the anterior face of the limb. The distal and clasping part of the leg is formed of a large, inflated basal portion on which three parts are inserted: a curved ‘movable finger’, and one long and one short palp.

Male non­clasping leg (description based on trunk leg 3, right side) elongate in shape with the typical (for spinicaudatans) number and arrangement of lobes and limb parts. The medial margin is subdivided into a distinct proximal endite and four more distal endites gradually becoming smaller from proximal to distal. The proximal endite is elongate and pointed and has rows of setae on both sides. The remaining four endites are simple lobes, each having two rows of slender setae. On the fifth endite is attached a long palp that is weakly biarticulate and bears distal ornamentation (probably sensory). Distal to the fifth endite, and articulated to the limb, is an elongate setose endopod (length: 2/3 of palp). Laterally is attached a tubular epipod, pointing basally, and a large exopod protruding basally into a slender setose lobe and distally into a broader, spatula­like setose lobe.

In females, the eggs are carried by dorsal projections of some of the posterior trunk legs. The telson is laterally flattened and has dorsally two rows of about 12­13 spines of varying size with a pair of telsonal setae placed in between the two rows. The telson ends dorsally in a pair of backwardly curved large spines pointing in two different directions. More ventrally, articulated to the telson, is a pair of caudal claws (= furcae) with a few slender setae at the dorso­proximal margin and rows of short scales dorso­distally.

Etymology. In 2004 a matrimonial alliance was made between Crown Prince Frederik of Denmark and an Australian, Mary Elizabeth Donaldson. Since the present work is the result of another Danish­Australian alliance, we have chosen to name the new species for the new Crown Princess of Denmark, Mary Elizabeth.

Remarks. Few clam shrimps of the family Cycizidae have been described from Australia (Richter & Timms in press), and Caenestheriella mariae differs from all of these. The number of genera within the Cyzicidae is currently under debate (see Richter & Timms in press), but by using the generic criteria suggested by Daday (1914), this species keys out as Caenestheriella , since it has the combination of a backwardly pointing occipital condyle and a pointed rostrum. Daday’s (1914) generic criteria have been questioned by Brtek (1997) but were followed by Martin (1992) and Richter & Timms (in press). It is beyond the scope of this contribution to judge the validity of Daday’s generic criteria. No matter how the cyzicid genera are defined, Caenestheriella mariae sp. nov. remain a distinct species. Only one Australian species of Caenestheriella has been described previously: Caenestheriella packardi Brady, 1886 . This is the species Caenestheriella mariae sp. nov. most closely matches. The original description of Caenestheriella packardi by Brady (1886) is not detailed enough to allow for meaningful comparison, but the redescription by Sars (1895) shows that the head shape differs between the two species on several points. In both species the occipital condyle is pointed backwards, but in Caenestheriella mariae sp. nov. there is a hump before the tip, while this margin is straight in Caenestheriella packardi . Another difference is that the angle between the eye lobe and the rostrum is about 90º in C. mariae while this angle is nearly non­existant in Caenestheriella packardi . The eye lobe is more prominent in Caenestheriella mariae sp. nov. than in C. packardi . Other differences are the presence of broad distal lobes of the trunk limb exopods in Caenestheriella mariae sp. nov. (male, third leg), and the absence of distinct sculpturing between the growth lines of the carapace. In many other respects the two species are very similar.

Natural history. All five localities where Caenestheriella mariae sp. nov. has been found are small gnamma (rock) pools on granite outcrops (inselbergs), which is not the case for its presumed closest relative, Caenestheriella packardi . The pools are seasonal, usually filling in winter (July and August) and lasting a few weeks to a few months. Associated branchiopods include Branchinella longiriostris Wolf, 1911 Limnadia badia (Wolf, 1911) , and rarely Lynceus macleayanus (King, 1855) and Caenestheria n. sp. (B. Timms, unpublished data). Sometimes these pools are filled by summer storms, but C. mariae has not been found after such events, though Limnadia dahli Sars sometimes occurs (M. Zofkova, personal communication). Caenestheriella mariae normally is found crawling on the rocky bottom of the pools and not on the softer sediments, and appears to scrape algae from the rocky surface. It seems that C. mariae , like Branchinella longirostris and Limnadia badia , is restricted to gnamma pools, as it has not been found in other temporary pools (e.g. claypans, vegetated pools, samphire pans, salinas) in the area.

Figures

FIGURE 4. Scanning electron microscopy (SEM) of male paratypes of Caenestheriella mariae n. sp. (ZMUC CRU­ 4854). A, whole view from right side; B, frontal view; C, caudal region; D, dorsal row of spines on telson; E, caudal claws (= furcae); F, head region seen from left; G, distal margin of rostrum seen from anterior; H, head region seen from right; I, occipital condyle.