Ozestheria indica (Gurney,1906)

Padhye, Sameer M., 2020, Taxonomical account of the Indian spiny clam shrimps (Crustacea: Branchiopoda Spinicaudata) from the Smithsonian National Museum of Natural History, USA., Zootaxa 4801 (2), pp. 374-382 : 375-377

Ozestheria indica (Gurney,1906)

( Figs. 1 , 2 , Figs.3A & B )

Locality. Quarry pond on the east edge of Parapatti, Tamil Nadu, India (11.677 N, 78.163 E)

Material examined. Three males and three females ( USNM 1143235, Collection date: 14 th October, 1980. Deposited as Caenestheriella sp.)

Diagnosis: Scales observed on the endopod tip of both the male claspers (sensu Rogers, in press).

Description. Male. Head. Ocular tubercle not conspicuous, eyes circular and about 0.3 times the size of ocular tubercle, naupliar eye elongated, rostrum long, triangular with blunt apex, occipital condyle distinct, projecting, as long as its width at base ( Fig.3A ).

First antenna pedunculate with 15–19 irregular lobes; each lobe lined with aesthetascs.

Second antenna. Peduncle cylindrical about 0.3–0.4 times the head length, anteriorly lined with oblique rows of plumose setae. Antennal flagella exopod and endopod with 12–14 and 13–16 flagellomeres respectively. Each flagellomere cylindrical with 4–8 long anteriorly directed spines and 5–10 longitudinal row of setae on posterior side

Carapace. Length: 6.68 ± 0.4 mm; height: 2.68 ± 0.3 mm. Broadly oval, dorsal margin almost straight with projecting umbone. 16–20 visible carapace growth lines clearly seen, ventral margin evenly convex with dense setation ( Fig.1B )

Thoracopods. Twenty-two pairs of thoracopods present ( Fig.1A )

First two thoracopods modified into claspers in males. Clasper movable finger (endopod) broad anteriorly, narrowing posteriorly and hook shaped ( Fig. 1 C–D), tip lined with distinct curved scales ventrally ( Fig. 1E ). Large palp (endite V) two segmented in both claspers, length of both segments similar in first clasper; distal palpomere (endite V outgrowth) slightly elongated than proximal segment, in second clasper. Small palp (endite IV outgrowth) cylindrical in both claspers, about 3.5 times as long as broad; palm (endite IV) broadly rectangular, about 1.3–1.4 times as longer than broad ( Fig. 1C & D ); gripping area of the palm lined with spines which increase in size posteriorly, spines conical with pointed apex ( Fig.1E ).

Other thoracopods similar in structure (except for the two claspers) but reducing in size posteriorly (for thoracopod number please see Fig.1 A ).

Abdomen. Dorsal margin of the posterior body segments (last 11–12) with a dorsomedial posteriorly directed projection, increasing in size anteriorly, twice as long as wide, lined with 4–10 long posteriorly directed and curved spinules; longest spinule about 0.5 times the length of the projection; last 2–4 segments without such spinules but with single or bifurcated stout apices.

Telson broadly rectangular, dorsal margin lined with 15–25 bilaterally serrated pairs of spines broadly increasing in size posteriorly; longest spines about 0.8 times the width of cercopod base in length. Dorsal edge ending in a curved and pointed spiniform projection and nearly 0.6–0.7 times the length of the cercopod. Caudal filaments originating between the second and fourth pair of spines of the telson ( Fig. 2A ).

Cercopod long, about 1.2–1.4 times than the postero-medial edge of telson, narrowing distally; a few (exact number indeterminable, 5–8 seen) plumose setae present till about proximal 4/10 th, lined with pecten from apex to about middle of cercopod ( Fig. 2A ).

Female slightly smaller than male (length: 5.4 ± 0.3 mm; height: 2.4 ± 0.4 mm). Rostrum shorter and broader, rostral tip more acute; occipital condyle similar to male ( Fig. 3B ); dorsomedial posteriorly directed projection same as in male ( Fig. 2B ); telson edge less arched as compared to male; telson marginal spines size, number and arrangement similar to male; cercopod size, shape and rest of the characters similar to male ( Fig. 2B ).

Remarks. Recent study by Schwentner et al. (in press) has placed many species from the genus Cyzicus to Ozestheria based on the presence of scales on the male clasper; character which is clearly observed in this species, thus, justifying the shift to genus Ozestheria . Male telson morphology of this species matched with the earlier detailed description by Daday (1915) but the head morphology varied. The rostral tip was more elongated and head slenderer in these specimens. Head morphology is known to vary in members of this family ( Rogers et al. 2017). Female head of Ozestheria indica was broader than Cyzicus annandalei Daday, 1913 while the marginal spines number on telson was less in the latter ( Daday, 1915). As per Daday’s description of Cyzicus annandalei male, the male rostrum seems to be very long in contrast to Ozestheria indica . Type material of the former species was not accessible to compare the morphological differences. This species is currently known from South India and Sri Lanka ( Daday, 1915; Selvarajah & Costa, 1979; Rogers & Padhye, 2015).

Figures

FIGURE 1. Ozestheria indica. A, male habitus. B, carapace. C, male clasper 1. D, male clasper 2. E, male clasper gripping area of the palm. Scale bars: A & B—1 mm; C & D—0.2 mm; E—0.05 mm.

FIGURE 2. Ozestheria indica. A, male telson. B, female telson along with dorsal armature. Scale bars: A—0.2 mm; B—0.5 mm.

FIGURE 3. Ozestheria indica. A, male head. B, female head. C, Eulimnadia michaeli hermaphrodite head. Scale bars: A & B—1 mm; C—0.5 mm.