DECAPODA Latreille, 1802

Padate, Vinay P., Bhat, Mithila S. & Rivonker, Chandrashekher U., 2018, New records of two decapod crustaceans (Decapoda: Dendrobranchiata and Pleocyemata) from the Gulf of Mannar, India, Journal of Natural History 52 (33 - 34), pp. 2209-2220 : 2211-2212

Order DECAPODA Latreille, 1802

Suborder DENDROBRANCHIATA Spence Bate, 1888 Superfamily PENAEOIDEA Rafinesque, 1815 Family PENAEIDAE Rafinesque, 1815

Genus Metapenaeopsis Bouvier, 1905

Metapenaeopsis tarawensis Racek and Dall, 1965

( Figure 2 (a), 2(b))

Metapenaeopsis tarawensis Racek and Dall 1965, p. 46 , fig. 9A–D

Metapenaeopsis tarawensis: Starobogatov 1972, p. 408 , pl. 10, fig. 137a, b; Burukovsky 1974, p. 38, fig. 54a–c; Crosnier 1991, p. 241, figs. 54a–c, 55, 56 a–f

Metapenaeopsis tarawaensis: Hayashi 1986, p. 18

Material examined

Tuticorin fishing harbour, Tamil Nadu State, south-east coast of India, 1 ♂ 49.3 mm TL (GUMSMB/TTN/CRUS-25/1) .

Type locality

Gilbert Island (Tarawa group) .

Habitat and distribution

Metapenaeopsis tarawensis has been reported from the coral reefs (intertidal zone up to 23 m depth) of Maldives, Cocos-Keeling islands, Northern Australia, New Caledonia, Gilbert Islands and Polynesia ( Crosnier 1991).

Description

Carapace uniformly covered with short setae, spines and grooves concealed by setae. Rostrum high, prominently crested, 7-toothed, followed by low epigastric tooth ( Figure 2 (a)). Adrostral carina curves downward under fifth rostral tooth. Postrostral carina absent. Antennal, hepatic and pterygostomial spines present; branchiostegal spine absent. Orbito-antennal groove and cervical grooves prominent, hepatic crest short, blunt, not reaching pterygostomian spine anteriorly, terminates abruptly behind cervical groove posteriorly. Stridulating ridge absent ( Figure 2 (a)).

Antennular flagella unequal, ventral slightly longer than dorsal. Basal antennular article two times as long as distal segment, with long distolateral spine; anteromedian spine absent. Scaphocerite reaching third antennular article. Basal antennal article two times in length of scaphocerite.

Third maxilliped reaching distal end of basal antennular article. Pereiopods 1–3 chelate, 4–5 simple. All pereiopods with exopods. P1 short, reaching distal end of basal antennular article, basial and ischial spines strong. P2 long, reaching distal end of third antennular article. P3 longest, reaching distal end of antennular flagellum. P4–P5 short, not reaching beyond distal end of basal antennular article.

Abdomen setose, somites 1–2 without dorsal carina, somites 3–6 with strong median dorsal carina; somites 4–5 with posteromedian incisions; somite 6 with distinct tooth posteromedially ( Figure 2 (a)). Telson shorter than inner uropods, subapical fixed lateral spines 1 pair, movable lateral spines 3 pairs.

Petasma asymmetrical, reaching forward up to base of P3; distolateral portion of left valve spoon-shaped with short, blunt distal projection visible ventrally; distoventral portion of right valve pot-belly shaped, distal projection strongly curved, inserted perpendicular to left valve, and completely concealed by the left valve ventrally ( Figure 2 (b)).

Remarks

Racek and Dall (1965) described Metapenaeopsis tarawensis based on holotype female (38 mm total length) from Gilbert Islands (Pacific Ocean) . Their provided line diagrams of female carapace, petasma (dorsal and ventral views) and thelycum ( Racek and Dall 1965, fig. 9A–D). The present material largely resembles the description of the holotype, with the exception of the carination on abdominal somites 3–6. In the present specimen, somites 3–6 possess sharp dorsomedian carina, whereas the holotype is characterized by blunt carina on somite 3 ‘in its posterior 5/8’ and sharply carinated 4–6 somites ( Racek and Dall 1965).

Comparison of the present specimen with supplementary material from Ashmore Reef, Western Australia (MP-NA-12,635) revealed differences in the number of rostral teeth (9 teeth in the latter) as well as carination on abdominal somites (blunt carina on somite 3 and sharp carinae on somites 4–6 in the latter).

Figures

Figure 2. Metapenaeopsis tarawensis (a) male, lateral view; (b) petasma, ventral view. Scale bars: a – 10 mm, b – 1 mm.