Batheuchaeta anomala is an aetideid calanoid copepod known after both sexes (female 4.70-4.80 mm and male 4.05-4.20 mm in total length). Species recorded only in abyssopelagic in the regions of the Kurile-Kamchatka and the Aleutian trenches in the northern part of the Pacific Ocean. Females of the species are characterized by the presence of rostrum that is not typical for females of Batheuchaeta.
Female. Total length 4.70-4.80 mm. Abdomen 4.5 times shorter than cephalothorax. Rostrum present as rudiment, conic with small notch at apex. Lobes of posterior Th5 corners not visible dorsally, turned ventrally, nearly perpendicularly to longitudinal axis of body, not exceeding Th5 limits (ventral view). Genital segment asymmetrical: on the right - projection present reaching the midlength of the segment and covered with hair (dorsal view) and on the left - small swelling, also covered with hairs. Genital segment longer than 3 following segments; ventral swelling small, semicircle (lateral view). Genital field asymmetrical. A1 reaching posterior border of Abd3. Ri Mx1 with 15 setae. Oral parts typical of the genus. Denticles at Ri P1 arranged in row along distal border of external lobe.
Male. Total length 4.05-4.20 mm. Cephalothorax 3.5-3.6 times longer than abdomen. Rostrum conic, with small notch at apex. Th5 posterior corners (dorsal view) with small prominences. Anal segment very small, along posterior border of Abd2-Abd3 - rows of minute spinules. A1 broken. Ri2 A2 bears 14 (7+7) setae. Md palp base with 1 setae, Ri1 and Ri2 Md with 1 and 9 setae respectively. Spinules on external lobe Ri P1 arranged close to distal edge apically; external spine at Re1 P1 very little. P5 big: Ri of left leg of specific two-horn shape, Re2 with 2 beak-like projections at the place of joint with Re3, the latter ending as a little claw. Distal segment of right Re with lateral triangular projection, one specimen had 2-segmented Re another, 3-segmented.
Mostly abyssopelagic species (Markhaseva, 1986b), recorded also in lower bathypelagial. Stenothermic and stenohaline species.
Pacific Ocean: the Kurile-Kamchatka Trench area (Markhaseva, 1981, 1986b), the Aleutian Trench area (Markhaseva, 1996).
Type locality: 45°28N 155°04'E (Markhaseva, 1981).
13 females and 2 males from samples: 19, 41, 85, 102, 103, 105, 124, 126, 148, 165, 181, 197. See examined samples module.
Type Material: Holotype, female, 4.8 mm total length, N 1/64731, R/V "Vitjaz", 39th cruise, 45°28'N 155°04'E, Sta. 5612, sample 87; 31 August 1966, depth 9100 m, stratum of sampling: 0-4200 m, ring-trawl. Paratype, female length 4.8 mm, N 2/64732 from the same sample. Types are kept in the Zoological Institute, Russian Academy of Sciences, St. Petersburg.