Triparatanais meios Bamber & Chatterjee, 2010, sp. nov.
Creators: name: Bamber, Roger N
name: Chatterjee, Tapas
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Paratanaidae
Triparatanais
Triparatanais meios

description: Triparatanais meios sp. nov.
Figs 3, 4
Material examined: 1Ƥ, holotype (NMWZ.2010.001.0004), 1 manca, paratype (NMWZ.2010.001.0005), Wandoor (11°40.55’N, 92°45.12’E), Port Blair, South Andaman Island, salinity 35.5‰, intertidal sediments among macroalgae (Halimeda opuntia), December 2005; coll. TC. 1Ƥ, paratype (dissected, on slide: NMWZ.2010.001.0006), same locality data as holotype.
Description of female: body (Fig. 3 A) elongate, slender, 1.29 mm long, 6.5 times as long as wide, colour in alcohol translucent white, eyes black. Cephalothorax subrectangular, 1.15 times as long as wide, narrowing anteriorly, twice as long as pereonite 1, with small triangular rostrum, with one small lateral seta behind each eyelobe; eyes present, pigmented. Six free cylindrical pereonites, naked other than single anterolateral setae on pereonite 2; pereonite 1 half as long as cephalothorax, pereonites 2, 3, 4 and 5 progressively longer, pereonite 5 being 1.4 times as long as pereonite 1, pereonite 6 shortest, just shorter than pereonite 1 (all pereonites respectively 1.7, 1.5, 1.4, 1.3, 1.2 and 1.7 times as wide as long). Pleon of five free subequal pleonites bearing pleopods and pleotelson; pleonites 5.7 times as wide as long; each of pleonites 1 to 4 with one plumose, articulating lateral seta on each side; pleonite 5 with single simple lateral seta on each side. Pleotelson semicircular, short, 3 times as long as pleonite 5, 1.7 times as wide as long, laterally with paired setae above each uropod attachment, distally with two posterolateral setae.
Antennule (Fig. 3 B) of four articles, proximal article 2.3 times as long as wide, mesially with single longer dorsal and short inner and outer lateral setae, distally with outer seta longer than second article; second article as long as wide, 0.2 times as long as first, with single inner and outer distal setae; third article three times as long as second, distally extended to inner point, with fine inner and outer distal setae; fourth article minute, mounted subdistally on outer margin of third article, with three distal setae and single aesthetasc.
Antenna (Fig. 3 C) of six articles; proximal article compact, wider than long, with fine dorsodistal seta; second article twice as long as first, with single ventrodistal and dorsodistal setae; third article as long as first, naked, with stout dorsodistal spine; fourth article longest, 1.1 times as long as second, with one distal simple setae; fifth article 0.65 times as long as fourth with two distal setae; sixth article minute with three distal setae.
Labrum (Fig. 3 D) hood-shaped, apically setose. Left mandible (Fig. 3 E) with wide, crenulate lacinia mobilis, slightly crenulate pars incisiva, molar process robust with elaborate, extruding distal teeth; right mandible (Fig. 3 F) without lacinia mobilis, pars incisiva not distally bilobed. Labium (Fig. 3 H) simple, distally finely setose, without palp. Maxillule (Fig. 3 G) with nine scimitar-like distal spines, endite with setose outer margin, palp not fully recovered. Maxilliped (Fig. 3 J) palp first article naked, second article with two simple inner setae and single outer seta; third article with three inner simple robust setae; fourth article with five distal simple robust setae and outer simple seta; single inner spine on basis not exceeding distal margin of endites or of first palp article; endites (Fig. 3 I) characteristic of subfamily, with sparsely denticulate outer margin, two distal rounded tubercles but no inner spine. Epignath not recovered.
Cheliped (Fig. 4 A) compact, basis relatively slender, 2.26 times as long as wide; merus triangular, with one mid-ventral seta; carpus longer than basis, 2.5 times as long as wide, with two setae on ventrodistal margin, dorsally with single mesial and distal setae; propodus longer than wide, with single seta near articulation of dactylus, fixed finger shorter than palm, with one ventral seta and three setae along crenulate cutting edge; dactylus naked, longer than fixed finger.
Pereopod 1 (Fig. 4 B) longer than others, coxa and proximal end of basis not recovered; basis slender, about 3.7 times as long as wide; ischium compact with single seta; merus just longer than carpus, both with single dorsodistal seta; propodus 1.5 times as long as carpus, with single dorsal and ventral subdistal setae; dactylus naked, less than half as long as distinct, slender claw, both together 0.9 times as long as propodus. Pereopod 2 (Fig. 4 C) basis more compact than that of pereopod 1, 2.8 times as long as wide; merus short, onethird as long as basis, with short ventrodistal spine; carpus 1.3 times as long as merus, with paired molariform ventrodistal spines, but without dorsodistal seta; propodus, dactylus and unguis similar to those of pereopod 1. Pereopod 3 (not figured) similar to pereopod 2.
Pereopod 4 (Fig. 4 D) basis robust, 2.1 times as long as wide; merus one-quarter as long as basis, with molariform, marginally-setulose ventrodistal spine and mid-ventral microtrichia; carpus 1.5 times as long as merus, with dorsodistal seta, slender inner distal molariform spine and shorter outer ventrodistal molariform spine, both marginally-setulose distally, and mid-ventral microtrichia; propodus just shorter than carpus with mid-distal penicillate seta, dorsodistal seta, and ventrodistally with one longer and one shorter molariform, marginally-setulose spine; dactylus and unguis fused into claw, curved, together three-quarters as long as propodus. Pereopod 5 (Fig. 4 E) as pereopod 4, but longer distal molariform spine even more slender. Pereopod 6 (Fig. 4 F) as pereopod 4, but propodus with four additional scimitar-like distal spines adjacent to claw.
Pleopods (Fig. 4 G) all alike; basis naked, apparently without setulated fringe; endopod with single inner, seven distal, and single outer proximal plumose setae; exopod longer than endopod, without setae on inner margin, proximal plumose seta on outer margin separated from remaining 11 or 12 plumose setae.
Uropod (Fig. 4 H) basis naked, exopod of one segment, shorter than proximal endopod segment, with two distal setae; endopod of two segments, second segment 1.5 times as long as first, with three distal setae.
Male unknown.
Etymology: from the Greek meion – less, alluding to the unusually (for the family) small size of adults of the present species.
Remarks. Other than the antennule, the morphology of the present species accords closely with those of species of Paratanais, which may be regarded as a sibling genus (see remarks above for the genus). The relatively sparse setation of the various appendages (when compared with species of Paratanais) is a feature attributed to the allometric influences of the very small size of the present species; most Paratanais species are between 3 and 5 mm in body length (e.g. Larsen, 2001; Bamber, 2008), twice or more the size of Triparatanais meios gen. et sp. nov. (hence the specific epithet).
description: Published as part of Bamber, Roger N & Chatterjee, Tapas, 2010, The new and the old: littoral tanaidomorph Tanaidacea (Crustacea: Peracarida) from the Andaman Islands, Indian Ocean, pp. 17-32 in Zootaxa 2558 on pages 23-26, DOI: 10.5281/zenodo.196949