Caulophacus (Caulophacus) elegans Schulze, 1886

Caulophacus (Caulophacus) elegans Schulze, 1886 View in CoL

Figs 14 View Fig , 15 View Fig ; Suppl. Tab. 11.

SYNONYMY: Caulophacus elegans Schulze, 1885: 438 , fig. 159 — nomen nudum in the fig. footnote; 1886: 46; 1887: 126; Koltun, 1967: 118.

MATERIAL. IORAS 5/2/2147: RV ‘ Akademik Mstislav Keldysh’ – 22, sta. 2309, trawl, N off the Bering Island, 55°13.24–12.02′ N 167°29.07 –26.7′ E, depth 3957–3978 m . IORAS 5/2/2151; 2152; 2155; 2157; 2158.1; 2162; 2164; 2167; 2168; 2169; 2172; 2173; 2174; 2175; 2179; 2180; 2180.1; 2184; 2185; 2186; 2187; 2191; 2194; 2195; 2199; 2202; 2204; 2207; 2208; 2210; 2211; 2212; 2214; 2216; 2218; 2236; 2245; 2260; 2261; 2269; 2275; 2296; 2299; 2306; 2308: RV ‘ Akademik Mstislav Keldysh’ – 22, sta. 2316, trawl, N off the Bering Island, 55°36.08–35.00′ N 167°23.04 –24.46′ E, depth 4200– 4294 m .

DESCRIPTION. BODY. The specimens have a mushroom shaped body typical for Caulophacus . Some specimens however are just fragments. Discoidal bodies are from 33 to 200 mm in diameter, 1.5–10 mm in thickness, with undulating edges of discs. Peduncles are tubular 2.5–20 mm in diameter.

SPICULES. MEGASCLERES. Hypodermalia and hypoatrialia are pentactins with rays having smooth and rounded outer ends or they have tubercles or numerous tubercles on the shafts close to the spicular center. The tangential rays of hypodermal and hypoatrial pentactins are 0.3–0.6 mm long, the ray directed inside the body is 0.5–0.7 mm long, these rays are 0.017 –0.038 mm in diameter. Choanosomal spicules are diactins and hexactins. Choanosomal diactins usually have a widening in the middle, sometimes four rudimental tubercles or they are stout, their outer ends are rounded and rough. Choanosomal diactins are 1.1–1.5/ 0.005 –0.011 mm. The diactins of the peduncle are 0.019 –0.022 mm in diameter; they are connected by numerous synapticular junctions. Choanosomal hexactins have smooth rays with rounded outer ends, that are 0.45–0.9/ 0.023 –0.044 mm in length.

Dermalia and atrialia are similar to each other in shape and generally in size. They are hexactins which have rays directed outside the body. Rays are pinular and smooth or slightly covered by tubercles; other rays have rounded or conically pointed, rough outer ends. Rarely dermal and atrial spicules are pentactins with a rudimental tubercle situated in place of the ray directed inside the body. The pinular ray of dermal hexactins is 0.096 –0.248 mm long, tangential rays are 0.067 –0.141 mm long, the ray directed inside the body is 0.048 –0.137 mm long, the diameter of these rays is 0.007 –0.011 mm; the diameter of the pinular part is 0.037 –0.044 mm. The pinular ray of atrial hexactins is 0.111 –0.340 mm long, tangential rays are 0.067 –0.144 mm long, the ray directed inside the body is 0.037 –0.118 mm long, the diameter of these rays is 0.007 –0.009 mm; the diameter of the pinular part is 0.026 –0.037 mm.

MICROSCLERES. Obviously two types of discoidal microscleres are known in these specimens. Some oxyoidal microscleres but likely they belong to other hexactinellids from close locations. Discohexasters have short principal rays, the rays are spiny and usually they have 5–6 secondary rays, rarely 1. Abnormal discohexasters are rare. The discohexasters are 0.086 –0.151 mm in diameter with primary rosette 0.011 –0.036 mm in diameter. Lophodiscohexasters often have tubercles carrying some additional discoidal rays on the smooth shafts; sometimes the secondary rays are of different sizes (lophoanysodiscohexasters).Thesecondaryraysoflarge lophodiscohexasters are short–spiny, in small spicules they look to be smooth and even sometimes tyloidal in shape (not completely developed). The number of secondary rays is from 4 to about 30. Rarely lophodiscodiasters were found. Lophodiscohexasters are referred to a single size class of spicules in spite the significant size variation. The gap of their size classes was observed in some specimens but in other the gap is different and in some completely absent. The diameter of lophodiscohexasters is 0.047 –0.324 mm with primary rosette 0.022 – 0.144 mm in diameter. The largest lophodiscohexaster was found in the specimen 5/2/2168 — 0.324 mm in diameter with the primary rosette 0.108 mm in diameter what is close to that described by Koltun (1967) (0.330 mm in diameter) which he considered to have allochthonic origin.

REMARKS. As it was observed, the specimens of different sizes: small and big (Suppl. Tab. 11) have very similar sizes of spicules. Moreover, Table 11 shows that the smallest specimen 5/2/2187 has the most spicules of larger sizes than larger specimens.

Among numerous species of Caulophacus (Caulophacus) the newly found materials are most of all similar to C. (Caulophacus) elegans in the presence of discohexasters (unlike discohexactins), shape of most spicules, but unlike the previously known species it has dissimilar dermal and atrial pinular hexactins. The dermal hexactins are smaller than the atrial ones in C. (Caulophacus) elegans and generally equal in the new specimens from the Bering Sea.

DISTRIBUTION. Bering Sea, E of Japan, 3680– 4220 m.