Rhopalaemon belindae ( Kemp, 1925 ) Ashelby & Grave, 2010

Ashelby, Christopher W. & Grave, Sammy De, 2010, A new genus of palaemonid shrimp (Crustacea: Decapoda: Palaemonidae) to accommodate Leander belindae Kemp, 1925, with a redescription of the species *, Zootaxa 2372 (1), pp. 369-378 : 371-377

publication ID	https://doi.org/ 10.11646/zootaxa.2372.1.29
persistent identifier	https://treatment.plazi.org/id/F85E8789-FFFA-FF91-FF75-A01CC73DFA07
treatment provided by	Felipe
scientific name	Rhopalaemon belindae ( Kemp, 1925 )
status	comb. nov.

Treatment

Rhopalaemon belindae ( Kemp, 1925) View in CoL new combination

Leander belindae Kemp 1925: 308–311 View in CoL , Figs. 12, 13a–e. — Kurien 1954: 71.

Palaemon (Palaemon) belindae . — Holthuis 1950: 7. — Ravindranath 1979: 189–191, Figs.1a–c View FIGURE 1 . — Pereira 1997: 50. Palaemon belindae . — Dutt & Ravindranath 1973: 124. — Jayachandran 2001: 209, Figs. 56a–e.

Material examined. Syntypes: (i) 1 male, pocl 5.9 mm; 1 ov. female, pocl 8.5 mm; Kilakarai , Ramnad District, Gulf of Mannar, S. India; 18.II.1913; leg. S.W. Kemp; RMNH.D.7691. (ii) 4 ov. female, pocl 7.9–9.1 mm ; 1 female, pocl 6.6 mm; rockpools, Kilakarai, Gulf of Mannar , S. India; coll. Zoological Survey of India; NHM 1924.1.25.17–21 . Non-type material: (i) 3 ov. females, pocl 7.6–9.7 mm; 3 females pocl 3.3–6.4 mm; 2 males, pocl 4.0– 4.9 mm; 1 individual, pocl 2.2 mm; amongst rocky blocks, Waltair Beach , Andhra Pradesh, India; 07.III.1980; leg. P. Noël; MNHN 8141 About MNHN . (ii) 6 ov. females, pocl 7.4–9.9 mm; 1 female, pocl 6.9 mm; 2 males, pocl 5.3–5.5 mm; amongst rocky blocks, Waltair Beach , Andhra Pradesh, India; 05.III.1980; leg. P. Noël; MNHN 8137 About MNHN .

Description. Carapace glabrous ( Figs. 1A, B View FIGURE 1 ). Rostrum ( Figs. 1C, D View FIGURE 1 ) slightly descendant with strong lateral ridge; much shorter than carapace, reaching to base of distolateral tooth of scaphocerite; armed with 7– 8 strong dorsal teeth and 2 ventral teeth; dorsal teeth without weakly constricted bases, posterior 2–3 teeth situated behind orbit, proximal-most situated at about one third carapace length; spacing between teeth roughly equal; tip of rostrum either simple pointed or bifid; double row of setae present in ventral unarmed portion, strong, single row of setae present between teeth both dorsally and ventrally. Antennal and branchiostegal teeth ( Fig. 1D View FIGURE 1 ) present, subequal in size, sub-marginal. Anterior margin of carapace distinctly concave in region of branchiostegal tooth. Branchiostegal groove originating dorsal to branchiostegal tooth, trending downwards, finishing at about one third carapace length, slightly lower than at its origin. Sub-orbital lobe produced, angular ( Fig. 1D View FIGURE 1 ); pterygostomial angle rounded. Béc ocellaire ( Fig. 1D View FIGURE 1 ) globular with slightly concave anterior margin, pronounced, slightly hooked median process, directed upwards at about a 45° angle, dorsal surface with strong concavity.

Eye ( Figs. 1E, F View FIGURE 1 ) well developed, with pigmented cornea; two concentric bands of pigment present on cornea, lower band usually faint; cornea slightly wider than stalk, approximately equal in length; ocellus present on dorsomedial side.

Antennular peduncle ( Fig. 1G View FIGURE 1 ) extending almost to distal margin of scaphocerite; basal segment 1.7 times as long as wide, slightly convex outer margin, stylocerite acute; distolateral tooth far exceeding laminar portion, extending to almost level with distal margin of penultimate segment; ventro-medial tooth present; statocyst with statolith; ultimate segment 1.6 times as long as penultimate, combined length slightly less than 0.7 times that of basal segment.

Dorsal flagellum of antennula fused for one quarter of length (approximately 8 segments fused, 28 free); free portion strongly serrate on ventral margin, with several aesthetascs on each segment.

Scaphocerite ( Fig. 1H View FIGURE 1 ) broad, laminar, 2.6 times as long as broad; outer margin straight, terminating in a tooth, falling short of distal margin of lamina; basal segment of antenna with reduced lateral tooth. Flagellum of antenna slightly longer than length of body.

Abdominal pleura furnished with plumose setae on ventral margin ( Fig. 1I View FIGURE 1 ); fifth pleuron posterodistal angle evenly rounded; sixth segment approximately 1.4 times length of fifth; posterolateral margin angular, without notch disto-ventrally; median lobe acute, with rounded ventral submedian process.

Thoracic sternal armature sexually dimorphic. Fourth thoracic sternite of females ( Fig. 4H View FIGURE 4 ) armed with sharp median tooth with strong, incomplete posterior ridge; fifth thoracic sternite with incomplete ridge; sixth and seventh with low rounded median bosses only; eighth sternite with small blunt median tubercle; in ovigerous and post-ovigerous females eighth sternite with flattened setose plate. Fourth thoracic sternite of males ( Fig. 4I View FIGURE 4 ) as in females; fifth to seventh thoracic sternites with low, rounded median bosses; eighth sternite with well developed, sharp median conical tooth.

Abdominal sternal armature sexually dimorphic. First to third abdominal sternites of females with small blunt median tubercle; fourth sternite unarmed; fifth with longitudinal ridge. In males, first to third abdominal sternites bearing narrow, parallel sided, blunt tipped tooth; fourth abdominal sternite unarmed; fifth abdominal sternite as in females. Pre-anal plate ( Fig. 4A View FIGURE 4 ) armed with well developed tooth in both sexes.

Mandible ( Fig. 2B View FIGURE 2 ) with three segmented palp; basal segment twice length of second segment, terminal segment 1.2 times length of basal segment; outer margin of palp fringed with simple and pappose setae, approximately 5 simple apical setae, disto-medial margin of second segment with single, long, simple seta. Incisor process of mandible with 3 teeth on right mandible, middle one smallest, and 4 teeth on left mandible, middle 2 smaller than outer teeth; molar process with 4 teeth of varying sizes. Paragnaths ( Fig. 2A View FIGURE 2 ) covering about half mandibles; alae formed by broad, transverse broadly oval, distal lobes, ventromedial lobes triangular. Corpus short, narrowly separated medially; base with two carinae. Epistome ( Fig. 2A View FIGURE 2 ) triangular with rounded anterior angle and strong anteromedian carina. Labrum ( Fig. 2A View FIGURE 2 ) narrow, rectangular. Maxillula ( Fig. 2C View FIGURE 2 ) with lower lacinia sub-rectangular, smaller and narrower than upper lacinia, with stout setae distally; upper lacinia with several distal spines and stout setae; with single simple seta on upper margin; palp with bifid tip; upper process naked, lower process broad with setiform process on ventral tubercle. Maxilla ( Fig. 2D View FIGURE 2 ) with upper lacinia deeply cleft, ending in several stout, plumose setae, several simple setae on upper margin; palp well developed, broad with few plumose setae on outer margin; scaphognathite large, fringed with plumose setae. First maxilliped ( Fig. 2E View FIGURE 2 ) with endites separated by distinct notch; palp slender, slightly twisted, with single subterminal simple seta and terminal plumose seta; exopod well developed, slender, furnished with plumose setae distally; caridean lobe well developed, broad, fringed with plumose setae; epipod large, bilobed, lobes sub-rectangular. Second maxilliped ( Fig. 2F View FIGURE 2 ) with broad rectangular ultimate segment; penultimate segment broadly triangular, with convex, semicircular upper margin; exopod much longer than endopod; epipod and well developed podobranch present. Third maxilliped ( Fig. 2G View FIGURE 2 ) pediform; ultimate segment 0.75 times length of penultimate; ischiomerus broadening distally, with strongly curved dorsal margin; exopod 0.7 times length of ischiomerus; epipodal plate broadly ovate; two arthrobranchs present, one rudimentary and obscured by larger.

Well developed pleurobranchs present on all thoracic legs. First pereiopod ( Fig. 3A View FIGURE 3 ) overreaching scaphocerite by length of fingers; basis approximately 0.6 times length of ischium; ischium disto-ventrally expanded; merus 1.3 times length of ischium; carpus 1.9 times as long as merus and slightly expanded distally; chela ( Fig. 3B View FIGURE 3 ) 0.8 times length of carpus, fingers equal to palm, with tufts of setae; carpal-propodal brush present. Second pereiopod ( Fig. 3C View FIGURE 3 ) extending beyond scaphocerite by half length of palm of chela; ischium 3.5 times length of basis; merus 1.3 times length of ischium; carpus 0.75 times length of merus, strongly expanded distally; chela ( Fig. 3D View FIGURE 3 ) about 1.7 times length of carpus; fingers approximately 0.4 times length of chela, 0.7 times length of palm, cutting edges covered with stout setae, proximally without dentition. Ambulatory pereiopods robust, broadly similar in length. Third pereiopod ( Fig. 3E View FIGURE 3 ) overreaching scaphocerite by length of dactylus; ischium 2.1 times length of basis; merus twice length of ischium; carpus 0.5 times length of merus, equal in length to ischium; propodus 2.0 times length of carpus, equal in length to merus, distally dilated, 1.3 times wider distally than proximally, ventral margin of dilated portion armed with 4 single spines and a distal pair, a further spine occasionally present further along margin; dactylus, stout, simple, strongly curved, about 0.3 times length of propodus. Fourth pereiopod ( Fig. 3F View FIGURE 3 ) reaching end of scaphocerite; ischium 2.3 times length of basis; merus 2.4 times length of ischium; carpus 0.5 times length of merus, slightly longer than ischium; propodus slightly less than 2.0 times length of carpus, distally dilated, 1.3 times wider distally than proximally, ventral margin of dilated portion armed with 4 single spines and a distal pair, a further spine occasionally present further along margin; dactylus stout, simple, strongly curved, about 0.3 times length of propodus. Fifth pereiopod ( Fig. 3G View FIGURE 3 ) falling short of distolateral tooth of scaphocerite by length of dactylus; ischium 2.0 times length of basis; merus 2.4 times length of ischium; carpus 0.5 times length of merus; propodus 2.1 times length of carpus, distally dilated, 1.3 times wider distally than proximally, ventral margin of dilated portion armed with 4–5 single spines and a distal pair, a further spine occasionally present further along margin, grooming brush ( Fig. 3H View FIGURE 3 ) comprises 1 poorly developed row of serrulate setae hidden between ultimate and penultimate spines; dactylus stout, simple, strongly curved, about 0.35 times length of propodus.

First pleopod sexually dimorphic in proportions, lacking appendix interna in both sexes; in males endopod 0.5–0.6 times length of exopod, both exo- and endopods fringed with plumose setae but medial portion of inner margin of endopod devoid of plumose setae, with 7 spines ( Fig. 4B View FIGURE 4 ); in females, endopod approximately 0.4 times length of exopod. Second to fifth pleopods broadly similar with endopod being slightly shorter than exopod, bearing appendix interna. Second pleopod of males with appendix masculina; about 1.4 times length of appendix interna ( Fig. 4C View FIGURE 4 ), furnished with 8 lateral and 3 apical simple setae.

Telson ( Fig. 4D View FIGURE 4 ) 1.1 times length of sixth pleonite; length:width ratio 3:1 proximally narrowing to 7.8:1 distally; dorsal surface with 2 pairs of spines and 1 pair of simple setae subdistally on median process; proximal dorsal tuft of about 10 simple setae present; proximal pair of spines situated at about 0.55 of telson length, distal pair at about 0.7–0.75 length; marginal setae present in distal half only; posterior margin ( Fig. 4E View FIGURE 4 ) prolonged into acute process, with 1 pair of submedian plumose setae and 2 pairs of spines, inner pair about 3 times longer than outer pair; median process exceeding outer pair of spines.

Uropods ( Fig. 4F View FIGURE 4 ) broadly ovate, overreaching telson by 0.3 times length of endopod; exopod slightly longer than endopod, weak diarhesis present; mobile lateral spine of exopod overreaching fixed tooth by length of tip ( Fig. 4G View FIGURE 4 ).

Eggs 0.7 × 0.6 mm.

Colour pattern. According to Kemp (1925: 311): “Translucent, thinly speckled with yellow and dark green chromatophores and with a certain amount of scattered white pigmentation in the middle of the carapace. On the dorsal side of the abdomen at the hinder end of the second and third somites there was a lenticular patch of pale dull pink and the distal two thirds of the tail-fan were heavily spotted with dark green or yellow brown. All the legs were banded with blue and each also bore a light red patch at the distal end of the merus, carpus and propodus or palm. The eggs were dark grey or olive. Young specimens were always paler than adults.” Additionally, Kemp (1925: 309) noted: “there are two concentric rings of dark pigment on the cornea, but the lower one is usually faint”, whilst Ravindranath (1979: 190) remarked: “antennular flagellae bear dark (greenish-maroon) and pale (pink) alternating bands”.

Distribution and habitat. Currently known from two locations in the southern Indian state of Tamil Nadhu (Keelakarai, Kanyakumari), as well as Andhra Pradesh State (Visakhapatnam), from littoral pools.