Bathydorus sp.

aff. Bathydorus sp.

Fig. 13 View Fig .

MATERIAL. IORAS 5 /2/3838: RV ‘ Akademik M.A. Lavrentyev’ – 75, sta. 18, specimen 3–3, ROV ‘ Comanche’, 55.4382° N 167.2652° E, 1559 m GoogleMaps .

DESCRIPTION. BODY. The specimen is represented by a small fragment attached to a dead skeleton of Farrea .

SPICULES. MEGASCLERES. Hypodermal (and hypoatrial pentactins as well), rarely stauractins with conically pointed, rough outer ends. The tangential rays of these pentactins are 0.3–1.0 mm long, the ray directed inside the body is 0.5–1.0 mm long, these rays are 0.009 –0.034 mm in diameter. Choanosomal diactins 2.3–3.7/ 0.008 –0.014 mm have stout shafts or with a widening in the middle with rounded, rough outer ends.

Dermalia and possibly atrialia are stauractins, rarely tauactins. They have slightly rough rays with conically pointed or rounded outer ends. The rays of these stauractins are 0.085 –0.344 mm in diameter (n=27, avg: 0.192 mm, std: 0.065 mm), the diameter of these rays is 0.004 –0.013 mm.

MICROSCLERES. Oxyoidal microscleres have very thin rays. They are usually oxyhexasters and oxyhemihexasters with 1–3 secondary rays, often curved or sometimes oxyhexactins. The diameter of oxyhexasters is 0.144 –0.237 mm (n=25, avg: 0.170 mm, std: 0.020 mm), the diameter of their primary rosette is 0.007 –0.015 mm (n=25, avg: 0.008 mm, std: 0.002 mm). The diameter of oxyhexactins is 0.148 – 0.215 mm (n=8, avg: 0.175 mm, std: 0.021 mm).

REMARKS. Among the species of Bathydorus only B. servatus Topsent, 1927 ( 1928) has similar oxyoidal microscleres with such thin rays. But dermal stauractins are much smaller as well as oxyoidal microscleres are also smaller in the newly found material, besides dermal diactins are absent (unlike B. servatus ). Based on a small fragment, description of a new species does not seem reasonable, moreover, the spicule content may be not complete and thus the generic identification is also not perfect. Spicules of other hexactinellids — Farrea and Periphragella were also found in investigated spicule preparations so the specimen is obviously contaminated by foreign spicules.