dcsimg

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Euchaeta scotti Farran, 1908

This rather rare bathypelagic species was originally described by Farran (1908) from female specimens obtained from off Ireland. The male was correctly described for the first time by With (1915) from the Norwegian Sea. In the present study, the species was represented by 62 females and 9 males found in tows down to depths of more than 1000 m. These findings constitute the first record of the species from the Gulf of Mexico and Caribbean Sea. The females measured 5.91–6.16 mm in body length and 4.16–4.48 mm in prosome length, and the males 5.33–5.58 mm in body length and 3.75–4.00 mm in prosome length.

The female is characteristic in having a humped dorsal wall of the genital segment and a straightly sloping posterior side of the genital prominence (Figure 18b). In the male the hollow scoop-shaped serrated lamella and pointed digitiform process serve as distinguishing characters (Figure 18d–f).

Euchaeta vorax Grice and Hulsemann, 1968

Pareuchaeta striata Tanaka and Omori, 1968:257–258, figs. 3x, 4x, 21a-d.

FEMALE.—Body length based on 14 specimens, 6.41–6.75 mm. Prosome length, 4.58–4.91 mm. Viewed laterally, forehead (Figure 19a) with a pronounced frontal eminence. Rostrum well developed, straight in parallel to dorsal margin of forehead. Genital segment (Figure 19c) elongated, with a small, low tubercle composed of several closely contiguous ridges on left side posterior to genital prominence. Laterally, genital flange undivided along ventral edge and produced posteiorly into a lobe. Posterior ridge (pr) of genital field produced posteriorly, forming a conspicuous lobe extending far beyond distal end of genital flange. Posterior side of genital prominence merging into ventral wall of segment, forming a single smooth arch (Figure 19c).

Antennule reaching middle of genital segment Outer coxal lobe of maxillule with 5 large setae of equal size in addition to 2 or 3 minute setae proximally. First 2 exopodal segments of first leg (Figure 12e) incompletely fused, with a faint line of joint. First segment with a minute external spine; second and third segments each with a well-developed external spine. Second leg (Figure 19f) with 1-segmented endopod and 3-segmented exopod. External spines of exopod moderately developed, that of second segment being the largest. Incision posterior to second external spine of third segment not unusually deep.

MALE.—Body and prosome length of specimen 6.66 mm and 4.66 mm, respectively. Forehead (Figure 19g) with a low frontal eminence. Rostrum arising from a broad base, pointing straight downward. Posterolateral corners of metasome asymmetrical. Antennule reaching distal end of second urosomal segment. Exopod of first leg (Figure 19h) 3-segmented; external spine of second segment small, turned inward. Second (Figure 19i) to fourth legs similar to those of female except that external spines are smaller. Serrated lamella of left fifth leg (Figure 19k) in form of an elongated triangle with uniformly fine marginal teeth. Medially, lateral toothed margin approximating medial toothed margin toward distal end (Figure 19l). Digitiform process slightly longer than serrated lamella, with distal portion tapering into a curved process.

DISTRIBUTION.—The species was represented in the present study by 14 females and a single male, which are found in samples taken from depths exceeding 1000 m in the Gulf of Mexico and western Caribbean Sea. These findings are the first record of the species since its discovery in the eastern South Pacific and western North Pacific almost simultaneously by Grice and Hulsemann (1968) and Tanaka and Omori (1968), respectively.
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bibliographic citation
Park, Taisoo. 1975. "Calanoid copepods of the family Euchaetidae from the Gulf of Mexico and western Caribbean Sea." Smithsonian Contributions to Zoology. 1-26. https://doi.org/10.5479/si.00810282.196

Depth range

provided by World Register of Marine Species
bathypelagic
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copyright
WoRMS Editorial Board
contributor
Kouwenberg, Juliana [email]

Identification

provided by World Register of Marine Species
Possible confusions with Paraeuchaeta aequatorialis , P. rasa and P. eltaninae.
license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Kouwenberg, Juliana [email]