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Protohyale covelongensis sp. nov. (Figures 1–5) Type material. Holotype: male 11.07 mm SL (ZSI/ MBRC / D1–694), Covelong (12°47′09.6″N 80°15′19.0″E), associated with green seaweed Chaetomorpha antennina on intertidal rocks, 22 February 2020, Coll. Amit Kumar and Vinuganesh Arjunan. Paratypes. 3 males, 11.6 mm SL; 12.2 mm SL; 13.2 mm SL (ZSI/ MBRC / D1–695); 3 females, 10.9 mm SL; 12.5 mm SL; 12.1 mm SL (ZSI/ MBRC / D1–696); same collection data as holotype. Type locality. Covelong (12°47′09.6″N 80°15′19.0″E), intertidal rocks, Chennai coast, Tamil Nadu state, India. Etymology. The new species has been honored in the name of the type locality of the species: Covelong. Diagnosis. Anterior margin of lateral cephalic lobe vertical. Eye red, round, of medium size. Antenna 1 is slightly shorter than Antenna 2. Mandible molar strong; left lacinia mobilis 7‐dentate. Gnathopod 1 coxa with a shelf on posterior margin; basis broadening medially; basis and ischium with large hydrodynamic lobes. Gnathopod 2 sexually dimorphic in character. Palm of male gnathopod 2 nearly straight with 2 weak swells on the distal half, with a distal process and medial concavity. Propodus of male gnathopod 2 longer than wide, posterior margin with several tapering and plumose setae distally, dactyl nearly as long as palm almost reaching the paired palmar spines with tiny inner setae at defined distances. Pereopod 7 basis with a very large axe-shaped flange and a small median notch on the anterior margin, slightly broader than long, the anterior margin finely crenulate. Uropod 1 peduncle subequal in length with rami, inter-ramal spine reaching less than half of outer ramus. Uropod 2 peduncle outer ramus shorter than inner ramus, both rami with 2 marginal and 3 terminal spines. Uropod 3 short, uniramous, ramus subequal to peduncle which has 3 large spines apically. Telson completely cleft, bilobate, each half subtriangular with 3 lateral setae each. Description. Based on the male holotype, 11.07 mm. Head. Anterior margin of lateral cephalic lobe vertical. Eye red, round, of medium size. Antenna 1 (Figure 2- A 1) shorter than antenna 2 (Figure 2-A2), about 0.61x antenna 2; peduncular article 1 of antenna 1 scarcely longer than article 2, article 2 scarcely longer than article 3;flagellum 15-articulate with 1–2 aesthetascs on each article. Antenna 2 (Figure 2‐A2) long; peduncular articles 1–3 same length peduncular article 5 longer than article 4; flagellum more than twice the length of peduncle with 25 articles of which those near the base are short, all articles bearing small bunches of setae. Labium or upper lip (Figure 2 ‐Lab) covered with a patch of pubescence apically. Mandible (Figure 2 ‐Md) molar strong; left and right incisor 8-dentate; left and right lacinia mobilis 7-dentate. Labrum or lower lip (Figure 2 ‐Lbr) round, lobes densely pubescent. Maxilla 1 (Figure 2 ‐Mx1) inner plate slender, with 2 setae apically; outer plate stout, with serrate robust setae; palp uniarticulate, reaching slightly above the distal end of the outer plate, with apical seta. Maxilla 2 (Figure 2 - Mx2) outer plate slightly longer than the inner plate; apical setae of outer plate slightly longer than that of inner plate. Maxilliped (Figure 2 ‐Mxp) inner plate slightly shorter than outer plate, with 3 conical teeth apically, outer and apical margins with several setae; outer plate subovate, extending beyond half of palp article 2, with row of simple setae medially, slender setiform teeth and simple setae subapically; palp slender, 4- articulate; articles 1–2 with large spines on outer margins; article 3 apical margins with long setae; article 4 elongate, falcate, and slender with marginal setae not overlapping nail. Pereon. Gnathopod 1 (Figure 3 ‐MG1, C1) coxa with a shelf on posterior margin; basis broadening medially; basis and ischium with large hydrodynamic lobes, basis of gnathopod 1 with 2 posterior spines; merus with sharp posterodistal protrusion; propodus subtriangular in shape as with a small median hump covered with setae and larger than carpus; dactyl, tip reaching slightly beyond paired palmar spines. Gnathopod 2 (Figure 3 ‐MG2) basis with 4 posterior spines, coxa longer than broad (1.09x longer) with well-developed shelf on posterior margin; basis and ischium lobate anteriorly, merus protrusively rounded apically, carpus small, triangular, propodus longer than wide (1.93x longer), posterior margin with several tapering and plumose setae distally, palm nearly straight with 2 weak swells on the distal half, with a distal process and medial concavity, dactylus nearly as long as palm, almost reaching paired palmar spines with tiny inner setae at defined distances. Pereopods 3 and 4 normal. Pereopod 3 (Figure 3‐P3) longer than pereopod 4 (Figure 3‐P 4), similar; propodus of pereopod 3 with 2 proximal spines followed by 2 discontinuous and striated locking spines; dactylus slightly longer than half of propodus, with small subterminal setae posteriorly and one anterior seta. Pereopods 5–6 (Figure 3‐P 5, P 6) increasing in length posteriorly; coxa bilobate, basis of pereopods 5–6 with smooth posterior margins and a small medial depression. Pereopod 5 (Figure 3‐P 5) basis almost as long as broad. Pereopod 6 (Figure 3‐P 6) basis longer than broad (1.29x longer). Pereopod 7 (Figure 3‐P 7) basis with a very large axe-shaped flange and a small median notch on the anterior margin, slightly broader than long (1.14x broader), the anterior margin finely crenulate. Pleon. Epimeron 1 (Figure 4 ‐Ep 1–3) ordinary, rounded; epimeron 2 (Figure 4 ‐Ep 1–3) and 3 (Figure 4 ‐Ep 1–3) with acuminate hind corners. Uropod 1 (Figure 4‐U 1) peduncle subequal in length to with rami, inter-ramal spine reaching less than half of outer ramus (0.43x outer ramus), both rami each with 3 marginal spines and 4 terminal spines. Uropod 2 (Figure 4‐U 2) peduncle slightly shorter than rami, outer ramus length about 0.79 x inner ramus, both rami each with 2 marginal and 3 terminal spines. Uropod 3 (Figure 4‐U 3) short, uniramous, ramus with 5 terminal spines subequal to peduncle, peduncle sub-rectangular with 3 large spines apically. Telson (Figure 4‐T) completely cleft, bilobate, each half subtriangular with 3 lateral setae on outer margin. Female (sexually dimorphic characters). Similar to those of males except in the gnathopods and secondary sexual characters. Gnathopods 1–2 (Figure 5 ‐FG1, FG2) much smaller than those of males. Gnathopod 2 (Figure 5 ‐FG1) larger than gnathopod 1(Figure 5 ‐FG2). Gnathopods 1 and 2 propodus 1.8–2 times longer than wide. Preamplexing notch (Figure 4 ‐Pn) sharply incised; unguisial groove broad, oblique; posterodistal lobe slightly acuminate. Remarks Protohyale covelongensis sp. nov. is closely related to P. macrodactyla (Stebbing, 1899) but can be distinguished by several morphological characters. For instance, in P. macrodactyla, the male gnathopod 2 basis has 3 spines on the posterior margin, however in P. covelongensis sp. nov., the basis of gnathopod 2 has 4 spines on the posterior margin. In P. macrodactyla, antenna 1 flagellum consists of 13 articles while in P. covelongensis sp. nov., the flagellum of antenna 1 consists of 15 articles. In the male pereopods 6 and 7 of P. macrodactyla, the anterior margin shows presence of 5 spines while it shows presence of 6 spines in P. covelongensis sp. nov. Also, in P. macrodactyla, the anterior margin of merus of pereopods 3–4 shows presence of a single spine whereas in P. covelongensis sp. nov., it shows 3 spines. In P. macrodactyla, the propodus of pereopods 5–7 shows the presence of 4 spines on the posterior margin but in P. covelongensis sp. nov., the propodus of 5–7 pereopods shows the presence of 5 spines. Also, dactylus of pereopods 3–7 in P. covelongensis sp. nov. is more concave on the anterior side margins than that of P. macrodactyla. Peduncle of uropod 3 in P. covelongensis sp. nov. consists of 3 apical spines while 2 large apical spines on that part in P. macrodactyla. Protohyale covelongensis sp. nov. is different from P. chevreuxi (Barnard, 1916), from the Indo-Pacific region, by lacking a distinct hump on the palm of propodus of male gnathopod 1 while P. chevreuxi has an enlarged distinct hump on the same region along with a distinct distal process near the insertion of dactylus (Barnard, 1916). Protohyale covelongensis sp. nov. is distinct from P. honoluluensis (Schellenberg, 1938) from the Indo-Pacific region, as P. honoluluensis has a straight palm of gnathopod 2 without any process. Protohyale covelongensis sp. nov. can also be compared with P. guasave (Barnard, 1979) distributed in the North East Pacific region, however P.guasave is more similar to P. chevreuxi in having a prominent enlarged distinct midpalmar spine on male gnathopod 1, similar to that seen in species of Allorchestes Dana, 1849 and Parhyale Stebbing, 1897. Protohyale covelongensis sp. nov. is distinguished from other Protohyale species in having an inter-ramal spine reaching less than half of outer ramus (0.43x outer ramus). Also, the adult male of P. covelongensis sp. nov. can be further distinguished from the above species by having a distinct axe-shaped flange on the basis of pereopod 7. Some of the common morphological differences between Protohyale covelongensis sp. nov. and global congeners are listed in Table 1. Habitat. Associated with green seaweed Chaetomorpha antennina on intertidal rocks. Distribution. Known only from type locality. |
