Teleotanais indiaensis, Larsen & Sahoo & Ansari, 2013

Larsen, Kim, Sahoo, Gobardhan & Ansari, Zakir Ali, 2013, Description of a New Mangrove Root Dwelling Species of Teleotanais (Crustacea: Peracarida: Tanaidacea) from India, with a Key to Teleotanaidae, Species Diversity 18, pp. 237-243 : 238-242

Teleotanais indiaensis sp. nov. Larsen and Sahoo ( Figs. 1–3 )

Material examined. Holotype: non-ovigerous female, 2.2 mm (Reg. no. MMF 42742), Chorao Island , Goa, central west coast of India, 20 February 2011, intertidal . Paratypes (Reg. no MMF 42743): one non-ovigerous female (dissect- ed), same locality . Three non-ovigerous females, one manca, same locality; 19 non-ovigerous females, 21 mancae, Diwar Island, Goa, central west coast of India, 25 May 2013, intertidal .

Diagnosis. Cephalothorax shorter than pereonites 1–3 combined. Antennule without pigmentation; distal article incompletely fused with article 4 and bearing distal and subdistal aesthetascs. Fixed finger of cheliped with one subdistal, five inner, and three ventral setae. Uropodal endopod biarticulate.

Description. Female, body from holotype, 2.2 mm, appendages from dissected paratype.

Body ( Fig. 1A, B ) Slender, more than ten times longer than broad. Unevenly scattered black pigmentation present (similar to that of the Tanaidae genera Tanais and Zeuxo ) dorsally on all somites and chelipeds. Cephalothorax subrectangular, 1.2 times as long as wide, shorter than pereonites 1–3 combined, tapering to anterior with slight rostrum. Eye lobes and pigmented eyes present. Pereonite 1 shortest, pereonites 2–5 successively longer. Pereonite 6 longer than pereonite 3 but shorter than pereonite 4. Each pereonite bearing lateral setae. Pleonites subequal in size, all bearing pleopods, with single pair of articulate plumose midlateral setae on pleonites 1–4 and pair of simple setae on pleonite 5. Pleotelson semicircular, longer than last two pleonites combined, with two pairs apical setae, the longer of which one is long as uropod.

Antennule ( Fig. 1C ) shorter than cephalothorax. Article 1 more than twice as long as article 2, shorter than combined length of rest of antennule, with four setulate proximal setae, one simple and three setulate distal setae. Article 2 1.3 times longer than wide, with one simple medial seta, and two simple and four setulate distal setae. Article 3 almost square, with two simple distal setae. Article 4 incompletely fused with cap-like terminal article, together bearing two subdistal setae and aesthetasc, and four distal setae and aesthetasc.

Antenna ( Fig. 1D ) marginally shorter than antennule but less than half as thick. Article 1 naked and fused with cephalothorax. Article 2 longer than wide, naked. Article 3 marginally longer than article 4, with one dorsoproximal, one dorsomedial, and two distal setae, one being bayonetshaped. Article 4 1.25 times as long as article 5, with one long (longer than article 5), one simple, and one setulate distal setae. Article 5 with one long (longer than article 4), one simple, and one setulate distal setae. Article 6 min with one short and three long (longer than articles 4 and 5 combined) terminal setae.

Mouthparts. Labrum ( Fig. 1E ) with slightly pointed, setulose apex, only weakly demarcated from clypeus. Mandibles with broad, denticulate molar. Left mandible ( Fig. 2A ) with crenulate lacinia mobilis and incisor. Right mandible ( Fig. 2B ) without lacinia mobilis, incisor bifurcate, outer margin crenulate. Labium ( Fig. 2C ) wide, bilobed, inner lobe less than one third as wide as outer lobe, with setulose apex and small outer depression indicating rudiment of palp. Maxillule ( Fig. 2D, E ) with nine distal spiniform setae and five subdistal setules, palp with two distal setae. Maxilla not recovered. Maxilliped ( Fig. 2F ) with basis armed with long seta extending beyond end of palp article 2. Endites narrow- er than bases, with single outer seta, three short, sharp, spiniform distal setae, and rounded inner tubercle. Palp article 1 naked; article 2 with one outer and four inner simple setae. Articles 3 and 4 with eight inner apical setae each. Epignath ( Fig. 2G ) narrow and naked.

Cheliped ( Fig. 3A ) with basis as wide as long, bearing dorso-subdistal seta. Merus sub-triangular with two ventral setae. Carpus longer than propodus including fixed finger, with two ventrodistal setae and one small dorsal seta at each end. Propodus robust, with inner row of two shorter setae and one twice as long, with additional seta below dactylus insertion. Fixed finger with two ventral, one ventrosubdistal, and four inner setae, cutting edge expanded into blade-shaped structure. Dactylus with small inner seta.

Pereopod 1 ( Fig. 3B ) longer than other pereopods, coxa (not illustrated) with seta; basis shorter than three succeeding articles combined, naked. Ischium with one seta. Merus longer than carpus, with single simple ventrodistal seta. Carpus with four simple distal setae. Propodus longer than merus, with six simple distal setae and subdistal dorsal spine. Dactylus and unguis as long as propodus. Dactylus with medial seta, marginally longer than unguis.

Pereopods 2 and 3 ( Fig. 3C, D ) subequal, shorter and more compact than pereopod 1. Basis longer than three succeeding articles combined, with two dorsoproximal setulate setae. Ischium with one simple seta. Merus subequal to carpus, with one simple ventrodistal seta. Carpus with three simple ventrodistal setae. Propodus longer than merus, with four simple distal setae and subdistal dorsal spine. Dactylus and unguis combined as long as propodus. Dactylus marginally longer than unguis, former with medial seta,

Pereopods 4 and 5 ( Fig. 3E, F ) subequal. Basis stout, with one longer setulose ventromedial seta and three shorter setulose dorsoproximal setae. Ischium with two simple setae. Merus marginally longer than carpus, with two ventrodistal spiniform setae. Carpus with three distal spiniform setae and dorsodistal bone-shaped seta. Propodus as long as merus, with two ventrodistal spiniform setae, two dorsodistal distal setae as long as dactylus, and one setulate dorsomedial seta. Dactylus and unguis attached to ventral part of propodus, combined shorter than propodus, claw-shaped but not fused to each other.

Pereopod 6 ( Fig. 3G ) as pereopods 4 and 5 except basis with one ventroproximal setulose seta and propodus with seven dorsodistal distal setae and three small dorsodistal spines, without dorsomedial setulate seta.

Pleopods ( Fig. 2H ) with basal article bearing single inner plumose seta. Endopod rectangular, with one inner seta and nine outer setae, most distal is thickest with complex apex. Exopod leaf-shaped, with 18 outer setae.

Uropod ( Fig. 2I ) marginally longer than half length of pleotelson, its basal article with two small distal setae. Endopod with two articles of subequal length, article 1 with two simple distal setae, article 2 with four long (longer than endopod) simple and two short, setulose setae. Exopod marginally shorter than endopod, with two subequal articles, article 1 with one simple distal seta, article 2 with two long (longer than endopod), thick terminal setae.

Male unknown.

Remarks. The new species differs from the two previously described species of Teleotanais , T. warragamba and T. gerlachi , in the cephalothorax being shorter than pereonites 1–3 combined, the fixed finger of cheliped having two ventral, one ventro-subdistal, and four inner setae, and the uropodal endopod being biarticulate.

Although only three species of this genus have now been recorded, it is already clear that the genus has a cosmopolitan warm water distribution ( Brazil, West Atlantic; Florida and El Salvador, Gulf of Mexico; Nigeria, East Atlantic; Australia, Pacific; and now India, Indian Ocean). Cosmopolitan distributions are recorded for a majority of tanaidacean genera (at least those that are not monotypic), and this holds true for both the deep-sea and shallow-water fauna. This fact is a reminder that we still know very little about how these non-swimming animals, which have no dispersal phase, have attained such wide distribution ranges (see Larsen 2005 for review).

Unfortunately, the males of all three species of Teleotanais are currently unknown and this could be an important clue to its phylogenetic position. Lang (1956) found 36 specimens of this genus, Sieg and Heard (1983) obtained twelve from the Gulf of Mexico and more than 200 from Nigeria, and Bamber (2008) reported 19 specimens from Australia. In the present study we recorded more than 40 individuals, and none were of the male gender. If the males were of the feeding type typical of the Tanaidae , it is probable that some would have been found. If the males are of the non-feeding/ non-swimming type typical of Leptocheliidae , the chances of finding them would be smaller but still reasonable, given the many specimens collected. This leads us to suspect that the males of this genus is of the much rarer non-feeding/ swimming type found in the Paratanaidae and Leptognathidae, among others.

Few tanaid records exist from mangrove roots, but this may simply be a reflection of the fact that many ecologists shy away from this group because of the difficulties involved with their identification. This is exemplified by the lack of lower taxon identification seen in many records from mangrove roots habitats, usually only to order ( Odum and Heald 1972; Livingston et al. 1977; Nagelkerken and Velde 2004a, 2004b), or in a few cases to family ( Corrêa and Uieda 2008). Two notable exceptions are Lang (1956) and Sieg and Heard (1983), which both refer to Teleotanais . Their specimens were also collected from mangrove roots. While members of this genus have also been recorded from other habitats ( Lang 1956; Sieg and Heard 1983; Bamber 2008), this genus may have a special affinity to mangrove habitats.

Etymology. Named after the Indian subcontinent.

Figures

Fig. 1. Teleotanais indiaensis sp. nov. A, holotype, habitus, lateral view; B, paratype, habitus, dorsal view; C, antennule; D, antenna; E, labrum, lateral view. Scale bars: 1.0mm for A–B, 0.25mm for C–D, 0.1mm for E.

Fig. 2. Teleotanais indiaensis sp. nov. paratype. A, left mandible; B, right mandible; C, labium; D, maxillule, endite; E, same, palp; F, maxilliped; G, epignath; H, pleopod; I, uropod. Scale bars 0.1mm.

Fig. 3. Teleotanais indiaensis sp. nov. paratype. A, cheliped; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; G, pereopod 6. Scale bars: 0.25mm for A, 0.1mm for B–G.