Planche 1 issued from : E.L. Markhaseva in J. Mar. Syst., 1998, 15. [p.418, Fig.4]. As Xanthocalanus laptevorum. Female (from 77°41,4' N, 125°55,1' E). Ce = forehead (lateral); R = rostrum (ventral); PC = posterior corners of prosome; Ur = urosome; Pmd = mandibular palp; Gnth md = gnathobase of Md. Scale bars: 0.1 mm.
Nota : Prosome length : urosome length = 4.2. Rostrum filaments tiny, hardly visible. Posterior corners of prosome triangular. A1 24-segmented, reaching nearly the posterior end of prosome. Mx2 with 4, 3, 3, 3, 3 setae at 1st to 5th endites, 1 seta at 3rd-5th endites is transformed into a finely serrated spine ; distal part of Mx2 with 1 worm-like and 5 brush-like sensory setae. Endopodites 2 to 5 segments of Mxp with 4, 4, 3, 3+1, 4 setae.
Distribution
NZ: 1
Carte de distribution de Byrathis laptevorum par zones géographiques
bathypelagi: hyperbenthic. Depth: 1992-2000 m. For Markhaseva (1998, p.414) this species is attribued to Xanthocalanus with some doubt as it shares some features with Neoscolecithrix (setation on exopodite segments 1 and 2 of A2, composition of setae at the syncoxa of Mxp). The coarse serration of spines on 4th and 5th endites of Mx2 (typical of Xanthocalanus) is poorly pronounced.However, the setal composition of the distal part of Mx2 is similar to the phaennid type (single worm-like appendage), but the number of brush-like appendages is less (5) than in phaennids and Xanthocalanus. Also the number of setae (4) at the 1st endite of Mx2 is less than typical of Xanthocalanus, nevertheless, for the moment the species is tentatively placed in Xanthocalanus. According to Kosobokova & al. (2011, p.34) and Markhaseva & Renz (2011, p.66) the species fits in the genus Byrathis.
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