Sphaeromopsis jayaraji sp. nov. (Crustacea: Isopoda), a new species of intertidal Sphaeromatidae from the Andaman Islands, northern Indian Ocean Author Anil, Pathan text Nauplius 2022 e 2022009 2022-06-06 30 1 12 http://dx.doi.org/10.1590/2358-2936e2022009 journal article 10.1590/2358-2936e2022009 2358-2936 10904888 Sphaeromopsis jayaraji sp. nov. ( Figs. 2–6 ) Zoobank: urn:lsid:zoobank.org:act: EC4A356A-266F-4A7A-BF91-EEAA969CA69F Material examined (all material is from the South Andaman, Andaman Islands). Holotype : male ( 2.9 mm ), station Corbyns Cove, 11°37’48.3”N 92°45’14.0”E , South Andaman , Andaman Islands , intertidal, high-tide line sand, coll. Pathan Anil , 7 April 2017 ( PUMB 35104 ) . Paratypes : 4 males (2.7, 2.8, 2.9, 2.9mm ); 3subadult males(2.4,2.4, 2.6mm ); 2juveniles (2.0, 2.1 mm ); 2 ovigerous females (2.8, 3.0 mm); 3 non-ovigerous females (2.1, 2.1, 2.3 mm ), same data as holotype ( PUMB 35105 ; BAKRZRL 2704, 2705, 2706) . 2 males (2.5, 2.8 mm ); 5 subadult males (2.3, 2.3, 2.4, 2.6, 2.6 mm ); 3 juveniles (2.1, 2.3, 2.3 mm ); 1 ovigerous female ( 2.7 mm ); 2 non-ovigerous females (2.2, 2.4 mm ), station Chotta Balu, 11°30’39.00”N 92°40’55.00”E , South Andaman , Andaman Islands , intertidal, mid-tide line sand, coll. Pathan Anil , 9 April 2017 ( PUMB 35106 , 35107 ; BAKRZRL 2707) . Diagnosis. Body 2.5 times as long as wide; head with weakly developed rostrum; pereonites 2–7 with coxal plate sutures on lateral sides; pleon with posterior margin bearing 2 short, separate sutures at either side; pleotelson posterior margin produced to narrowly rounded apex with 5 setae; epistome widest anteriorly, with broadly rounded anterior margin and sub-parallel lateral margins, anterior margin with widely spaced plumose setae; pereopods 1–3 with setulose fringe on inferior margins of ischium, merus, carpus, and propodus; uropodal exopod longer than endopod, dorsal surface with 2 deep longitudinal mesial grooves; endopod lateral margin weakly sinuate with long setae, apex with deep mesial groove with plumose setae. Figure 2. Sphaeromopsis jayaraji sp. nov. , holotype male (2.9 mm) (PUMB 35104). A , dorsal view; B , lateral view; C , frontal lamina; D , pleotelson; E , uropods. Description of male holotype ( Figs. 2–6 ). Body 2.5 times as long as greatest width; head smooth,rostrum weakly developed ( Fig. 2A ). Coxae 2–7 subequal, coxae 2–4 posterior lateral margins triangular, coxae 5 slightly rounded on posterior lateral margin and more rounded laterally in pereonites 6–7 ( Fig. 2B ). Pleotelson 0.9 times wider than long, forming dorsal arch in posterior view and some scattered setae over surface; posterior margin produced to narrowly rounded apex with 5 setae, lateral margins folded ventrally ( Fig. 3A ). Figure 3. Sphaeromopsis jayaraji sp. nov. , holotype male (2.9 mm) (PUMB 35104). A , ventral view of pleotelson; B , antennula; C , antenna; D , penes. Antennula basal article about 1.9 times as long as article 2, inferior distal margin with one plumose seta; article 2 short, 0.27 length of article 1, superior margin with 2 widely spaced plumose setae, inferior distal margin with 2 plumose setae and 1 simple seta; article 3 about 1.3 as long as article 2, superior margin with 25 short acute setae, inferior mesial margin with 2 widely spaced plumose setae, distal margin with single plumose seta and dorsal distal margin with 4 long simple slender setae; flagellum 6-articled, extending near to posterior margin of pereonite 1, articles 3–5 each bearing aesthetascs ( Fig. 3B ). Antenna with peduncle article 2 being 1.2 times as long as wide, 1.1 as long as article 1, superior distal margin with 4 short acute setae, 1 long plumose seta, inferior distal margin with 1 long slender simple seta; article 3 is 1.4 times as long as wide, 1.2 as long as article 2, superior mesial margin with 2 widely spaced plumose setae, distal margin with single RS uni-serrated, single simple and single widely spaced plumose seta; article 4 1.5 times as long as wide, 1.7 times as long as article 3, superior margin with 3 widely spaced plumose setae, single long seta,dorsal mesial margin with single short widely spaced plumose seta, inferior distal margin with 4 long simple slender setae; article 5 1.9 times as long as wide, 2.0 times as long as article 4, superior mesial margin with 2 short widely spaced plumose setae, distal margin with single RS uni-serrated, single simple seta; flagellum with 10 articles, extending to mid pereonite 2 ( Fig. 3C ). Epistome 1.4 times as long for maximum length and width, and 1.6 times as long for median length and width, epistome widest anteriorly, anterior margin broadly rounded with widely spaced plumose setae, lateral margins straight to very weakly concave, postero-lateral margins elongated with weakly concave, posterolateral lobes extending to mid-length of labrum ( Fig. 2C ). Maxilliped endite lateral margin weakly sinuate, distal margin with 2 blunt RS, set in amongst 7 distal and single sub-distal circumplumose RS; mesial margin with single coupling hook and many short simple setae; palp article 2 mesial margin with 5 slender setae; article 3 mesial margin with 7 slender setae; article 4 mesial margin with 3 slender setae; article 5 mesial margin with 5 slender setae ( Fig. 4A ). Mandible incisor with 3 cusps, lacinia mobilis with 4 cusps;spine row with 3 serrate, 3 simple spines; molar process round ( Fig.4B ); palp article 1 about 0.6 times as long as article 2, article 2 distolateral margin with 5 bi-serrate setae becoming progressively longer distally; article 3 with 7 bi-serrate setae, terminal seta being longest ( Fig.4C ). Maxillule lateral lobe lateral margin fringed with simple short setae, apical margin with 7 RS, some inferiorly serrate, mesial lobe with 3 comb, 2 simple setae ( Fig. 4D ). Maxilla lateral and middle lobes with 4 curved nodular serrate RS; mesial lobe with 4 serrate RS, 3 pectinate RS ( Fig. 4E ). Pereopod 1 basis about 2.3 times as long as greatest width, superior margin with 3 short sensory palmate setae and many short setae, inferior distal margin with single long simple seta; ischium to propodus inferior margin fringed with short setae; ischium about 1.9 times as long as greatest width, inferior margin with several simple setae and many short setae, superior margin with 5 long distally bi-serrate setae; merus 0.4 times as long as ischium, inferior distal margin with 2 RS, superodistal angle with 3 bi-serrate setae; carpus as long as wide, subtriangular, inferodistal angle with single bi-serrate RS; propodus 2.8 times as long as wide, inferior margin with 2 bi-serrate RS and some long setae; dactylus secondary unguis curved, with 3 simple setae at base, superior margin with single short seta, distal margin with single long seta ( Fig. 5A ). Pereopod 2 basis about 3.9 times as long as wide, superior margin with 2 sensory palmate setae, single simple seta, and many short acute setae, inferodistal angle with single long simple seta; ischium to propodus inferior margin fringed with short setae; ischium about 3.2 times as long as greatest width, inferior margin with few long setae and several short setae, superior margin with 9 long distally biserrate setae; merus 0.4 times as long as ischium, inferior margin with 2 long simple setae and distally single RS, superior distal margin with 5 long distally bi-serrate setae; carpus inferior margin with 3 simple long setae, superior distal margin with 4 long distally bi-serrate setae; propodus about 0.6times as long as ischium, supero-distal corner with single long bi-serrate seta and single small short seta;dactylus secondary unguis curved, with 3 simple setae at base, superior margin with single short seta, distal margin single long seta ( Fig. 5B ). Figure 4. Sphaeromopsis jayaraji sp. nov. , holotype male (2.9 mm) (PUMB 35104). A , maxilliped; B , mandible; C , mandible palp; D , maxillula; E , maxilla. Pereopod 3 similar to pereopod 2. Pereopod 4 basis about 3.4 times as long as wide, superior margin with 3 sensory palmate setae and many short acute setae, inferior distal margin with single simple long seta; on ischium to propodus inferior margin fringed with many short setae; ischium about 2.9 times as long as greatest width, inferior margin with 3 simple long setae, superior margin with 8 long distally bi-serrate setae; merus about 0.6times as long as ischium, inferior margin with 2 simple long setae and distally single RS, superior distal margin with 7 long distally bi-serrate setae; carpus inferior margin with 3 simple long setae, superior distal margin with single sensory palmate seta and single simple short seta;propodus about 0.7times as long as ischium, inferior margin with 5 long simple setae, superior distal corner with single sensory palmate seta and single simple long seta; dactylus secondary unguis curved, with 3 setae at base and superior mesial margin with 2 short setae distal margin with single long seta ( Fig. 5C ). Pereopod 5 similar to pereopod 4. Figure 5. Sphaeromopsis jayaraji sp. nov. , holotype male (2.9 mm) (PUMB 35104). A , pereopod 1; B , pereopod 2; C , pereopod 4; D , pereopod 6; E , pereopod 7. Pereopod 6 basis about 3.5 times as long as greatest width, superior margin with 4 sensory palmate setae and many short acute setae, inferior distal margin with single long seta; on ischium to propodus inferior margin fringed with short setae; ischium about 2.5 times as long as greatest width, inferior margin with 3 simple long setae, superior margin with short acute setae and 7 long distally bi-serrate setae; merus 0.4 times as long as ischium, inferior margin with 2 simple long setae, superior distal margin with 6 long distally bi-serrate setae; carpus subequal in length to merus, inferior margin with 2 simple long setae and single uni-serrated RS; propodus about 0.8 times as long as ischium, superior distal margin with 2 long distally bi-serrate setae; dactylus secondary unguis curved, with 3 simple setae at base, superior margin with 2 short setae, distal margin single long seta ( Fig. 5D ). Pereopod 7 basis about 3.7 times as long as greatest width, superior margin with 5 sensory palmate setae and many short acute setae, inferior distal margin with single long seta; ischium to propodus inferior margin fringed with short setae; ischium0.6 times as long as basis, 6 times as long as greatest width, inferior margin with 2 simple long setae, superior margin with 6 long distally bi-serrate setae; merus 0.4 times as long as ischium, inferior distal margin with single long simple seta, superior distal margin with 4 long distally bi-serrate setae; carpus subequal in length to merus, superior distal margin with 2 long distally bi-serrate setae, 4 bi-serrate RS, inferior distal margin with 2 uni-serrated RS; propodus about 0.9 times as long as ischium, inferior margin with single simple long seta, superior distal margin with single sensory palmate seta and single simple long seta; dactylus secondary unguis curved, with 3 simple setae at base, superior margin with 2 short setae, distal margin single long seta ( Fig. 5E ). Penes elongate, slender, tapering to narrowly rounded apices, length more than 6 times basal width, lateral margins with proximally directed hand-like scales on distal third ( Fig. 3D ). Pleopod 1 exopod and endopod with 22 and 10 PMS respectively; exopod 1.4 times as long as wide, lateral margin weakly straight, distally narrowly rounded and mesial margin weakly convex; endopod 1.3 times as long as wide, distally narrowly rounded, lateral margin strongly convex with short setae and mesial margin concave; sympodite0.6 times as wide as long, mesial margin with 3 coupling hooks ( Fig. 6A ). Pleopod 2 exopod and endopod with 23 and 9 PMS respectively; appendix masculina arising sub-basally, straight with parallel lateral margins from proximal to mesial, distally broad with rounded apex, appendix masculina 0.8 as long as endopod, projects slightly beyond by one third of its length; sympodite with 3 distomesial coupling hooks ( Fig. 6B ). Pleopod 3 exopod and endopod with 22and 10 PMS respectively; sympodite with 2 distomesial coupling hooks ( Fig. 6C ). Pleopod 4endopod narrower than exopod, mesial margins with some fine simple setae ( Fig.6D ). Pleopod 5, exopod longer than endopod, with incomplete transverse suture distally, bearing 3 scale patches (2 distally and 1 above the transverse suture) ( Fig. 6E ). Uropodal exopod lateral margin straight, smooth with plumose setae, apex concave with 3 plumose setae and mesial proximal margin weakly convex with simple setae, distal margin concave with plumose setae;dorsal surface of the exopod with2 deep mesial longitudinal grooves; endopod lateral margin weakly sinuate with long setae, apex with deep mesial groove and plumose setae, mesial anterior proximal margin weakly concave with long setae, distal margin convex with plumose and simple setae ( Fig. 2E ). Female . Slightly differs from male, particularly pleotelson posterior margin elongation less than in male, uropod rami are smaller than in male, exopod subequal or smaller than endopod and differs from male in sexual characters. Remarks . Sphaeromopsis jayaraji sp. nov. can be recognized by the epistome being widest anteriorly, with a broadly rounded anterior margin and sub-parallel lateral margins; the anterior margin has widely spaced plumose setae; the uropodal exopod is longer than the endopod and the dorsal surface has two deep mesial grooves running from anterior to posterior margin; the endopod lateral margin is weakly sinuate with long setae, apex has deep mesial groove with plumose setae. Sphaeromopsis jayaraji sp. nov. is most similar to S. sikata , which was also described from intertidal habitats of South Andaman. Both species share some characters such as pleotelson posterior margin produced with narrow apex and pleon with posterior margin bearing two sutures at either side. The new species differs from S. sikata in pleotelson lateral margins being folded ventrally( vs. not folded ventrally), epistome apical margin broadly rounded with plumose setae and straight lateral margins ( vs. triangular apex, lateral margins distinctly concave), uropodal exopod lateral margin smooth with plumose setae ( vs. lateral distal margin is serrate with three teeth), exopod dorsal surface with two deep mesial longitudinal grooves ( vs. dorsal surface smooth, without grooves), and appendix masculina distally broad with rounded apex ( vs. narrowly rounded apex). Figure 6. Sphaeromopsis jayaraji sp. nov. , holotype male (2.9 mm) (PUMB 35104). A , pleopod 1; B , pleopod 2; C , pleopod 3; D , pleopod 4; E , pleopod 5. Sphaeromopsis jayaraji sp. nov. is also similar to S. persikolpos , both species with a produced pleotelson (which is also shared with S. sei ), but differ in the pleon posterior margin bearing two sutures at either side ( vs. single suture), epistome with straight lateral margins ( vs. concave lateral margins). Sphaeromopsis jayaraji sp. nov. differs from S. sei in having uropodal exopod lateral margin smooth with plumose setae ( vs. serrate). Distribution . Known only from the type locality, South Andaman, Andaman Islands. Etymology . This species is named in honour of Dr. K.A. Jayaraj, Assistant Professor, Department of Ocean Studies and Marine Biology, Pondicherry University, the mentor of the author and a well-known ecologist and taxonomist in India .