Audulla sindhu, Thacker & Myers & Trivedi, 2025

Audulla sindhu sp. nov.

( Figs. 1A View FIGURE 1 , 2–3 View FIGURE 2 View FIGURE 3 )

Audulla chelifera Sivaprakasam, 1969: 564–566 View in CoL , fig. 7. (not Audulla chelifera Chevreux, 1901 View in CoL ).

Type material. Holotype, male, 5.0 mm ( LFSC.ZRC-221 ), Veraval (20°54'35"N 70°21'09"E), 16 January 2024, coll. D.R. Thacker GoogleMaps . Paratypes, 8 males, 4–6 mm ( LFSC.ZRC-222 ), data same as for the holotype GoogleMaps .

Etymology. The specific epithet sindhu is derived from the historical name of Arabian Sea the “Sindhu Sagar”.

Distribution and habitat. Audulla sindhu sp. nov. is reported from Cape Comorin and Pamban, Tamil Nadu State, India Sivaprakasam (1969), Veraval coast of Gujarat State (present study). In Veraval it was found among the algal beds spread along the intertidal region of the coast.

Description. Based on male, 5.0 mm.

Head. Eyes medium. Antenna 1 subequal to antenna 2. Article 1 0.63 x as long as article 2; article 2 1.41 x as long as article 3; accessory flagellum 6 articulated. Antenna 2 peduncular article 4 subequal to article 5; flagellum paddle-shaped, 1.25 x as long as peduncular article 5. Labrum broader at distal end and narrower at proximal end, distal margin with minute setae. Labium inner lobes well developed, oval in shape; outer lobes apically rounded covered with minute setae. Right mandible with 5 dentate incisors; 4 dentate lacinia mobilis; accessory setal row with 8 setae, palp 2 articulate, article 1 upper middle part slightly swollen, article 2 apically setose; Left mandible with 5 dentate incisors, 3 dentate lacinia mobilis, accessory setal row with 8 setae. Maxilla 1 inner plate with 6 long plumose setae and 3 small simple setae; outer plate with apical 9 dentate setae; palp 2 articulate, article 2 with several apex setae. Maxilla 2 inner plate broadened apically, with distinct oblique row of setae. Maxilliped inner plate well developed, with several apical and marginal plumose setae; outer plate with 4 apical long, thick plumose setae, 9 marginal dentate spines of gradually decreasing size, several setae on the upper face; palp 4 articulated second article longest; article 4 smallest, apical claw absent.

Pereon. Gnathopod 1 coxa subrectangular, ventral margin with small setae; basis 1.18 x as long as anterior margin of carpus; carpus with 5 tufts of setae on posterior margin and 3 tufts of setae on medial surface; propodus oval, subequal to anterior margin of carpus; palm subchelate, lined with unequal sized setae; dactylus subequal to palm. Gnathopod 2 coxa subrectangular, 1.48 x as long as broad; basis both margins moderately setose; carpus triangular, anterodistal corner with 2 setae, posterodistal corner with a tuft of several setae. Propodus subrectangular with posterodistal corner produced, 1.26 x as long as basis, anterior margin with 3 tufts of setae on distal end, entire posterior margin with several tufts of setae, palm with a small protuberance at the base of the dactylus; dactylus longer than palm, slightly bulged above the base, posterior margin dentate. Pereopod 3 coxa subrectangular with several small setae on ventral margin; basis rectangular with 4 small setae on posterior margin, anterior margin with several small and 2 medium sized setae; carpus subequal to propodus; dactylus 0.57 x as long as propodus. Pereopod 4 coxa subrectangular, ventral margin with 1 seta; basis rectangular with 2 small and 1 long seta on anterior margin, posterior margin with 3 medium sized setae, posterodistal corner with 3 medium sized setae; carpus subequal to propodus; dactylus 0.40 x as long as propodus. Pereopod 5 coxa bilobed, basis narrower at distal half, anterior margin with 4 small robust setae, anterodistal corner with 1 long and one short setae; merus 1.30 x as long as carpus; propodus 2.39 x as long as carpus; dactylus 0.27 x as long as propodus. Pereopod 6 coxa ellipse; basis subrectangular with 4 small setae on anterior margin and 1 long robust seta on posterior margin, anterior margin with 4 small robust setae, anterodistal corner with 2 robust setae, posterior margin with few small setae, merus 1.27 x as long as carpus; propodus twice as long as carpus; dactylus small, 1/4 of the length of the propodus. Pereopod 7 similar to pereopod 6 except, last 2 articles are in reversed direction.

Pleon. Epimeron 1 with almost straight ventral margin, posteroventral corner developed into a small notch, bearing 1 small setae. Epimeron 2 ventral margin rounded, posterodistal corner produced into a small notch, bearing 1 small setae. Epimeron 3 ventral margin rounded, posterodistal corner produced into a small notch, bearing 1 small setae, posterior margin with 1 medium sized setae located on the middle. Uropod 1 peduncle inner margin with 4 small robust setae with 1 long robust seta on distal corner; outer margin with 3 small robust setae and with 1 medium robust seta on distal corner, inter-ramus spur reaches 1/3 of the endopod; endopod as long as peduncle, outer margin with 4 small robust setae, inner margin bare; exopod 0.87 x as long as endopod. Uropod 2 peduncle subequal to exopod, inner margin with 3 small robust setae and 1 long robust seta at distal corner, outer margin with 3 small robust setae; exopod 1.2 x as long as endopod. Uropod 3 peduncle 1.14 x as long as subequal rami. Telson as long as broad, with a triangular notch on the distal margin, each arm with 1 small robust seta, 2 hair line setae on each lateral margin.

Remarks. Audulla sindhu sp. nov. is classified under a genus Audulla Chevreux, 1901 as it is having robust and elongated peduncles of both pairs of antennae, antenna 2 flagellum paddle-shaped, mandible palp robust and maxilla 1 inner plate obliquely truncate. But A. sindhu sp. nov. can be differentiated from its only congener Audulla chelifera Chevreux (1901) in the following characters: antenna 2 flagellum has 12 articles (fig. 2, A2) (vs. 8 articles in A. chelifera Chevreux, 1901 , fig. 57), maxilla 1 inner plate has 6 long setae and 3 short setae (fig. 2, Mx1) (vs. 8 long setae in A. chelifera Chevreux, 1901 , fig. 59), maxilliped outer plate with 9 marginal dentate setae and several setae on upper face and (vs. outer plate with 8 marginal dentate setae and upper face bare in in A. chelifera Chevreux, 1901 , fig. 60); gnathopod 2 propodus, sparsely setose and 1.8 x as long as broad (fig. 3, G2) (vs. densely setose and 1.5 x as long as broad in A. chelifera Chevreux, 1901 , fig. 62), uropod 1 inter-ramus spur reaches 1/3 of the endopod (vs. inter-ramus spur absent).

Sivaprakasam (1969) recorded A. chelifera on the basis of specimens collected from Cape Comorin and Pamban located in the Tamil Nadu State of India.The description and figures of A. chelifera given by Sivaprakasam (1969) shows similarities with A. sindhu sp. nov. in having characters such as: gnathopod 2 propodus comparatively less setose and 1.7 x as long as broad, gnathopod 1 dactylus posterior margin serrated (vs. propodus densely setose and 1.5 x as long as broad; gnathopod 1 dactylus not serrated in A. chelifera ). These characters suggest that A. chelifera recorded by Sivaprakasam (1969) from Tamil Nadu is showing more affinities to A. sindhu sp. nov. So, we herewith confirm that the records of A. chelifera by Sivaprakasam (1969) from Tamil Nadu State, India, is of A. sindhu sp. nov. only.