Chevroderma cuspidatum Ivanov & Scheltema 2008, n. sp.
Creators: name: Ivanov, Dmitry L.
name: Scheltema, Amélie H.
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Caudofoveata
Chaetodermatida
Prochaetodermatidae
Chevroderma
Chevroderma cuspidatum

description: Chevroderma cuspidatum n. sp.   
(Figures 1A, 2, 3, 4A–C, 24A; Table 1)  
 Type material: Holotype USNM 1112616. Paratypes: USNM; TAML; ZMUM Le1-166 (type locality); Le1- 164 (DGoMB, MT2 /2); Le1-165 (DGoMB, MT3 /3).   
 Type locality: Gulf of Mexico, 28°13.22'N, 89°29.77'W, 983 m (DGoMB, MT3 /1, 16.06.2000).   
 Material examined: Gulf of Mexico, 564 specimens (Table 1).   
 Diagnosis: Small (<3 mm), slender, smooth, translucent, posterium often longer than trunk; sclerites adpressed; trunk sclerites short (to 120 µm), thin (to 5 µm), curved, sausage-shaped, blade as a small, sharp nipple; sclerites fringing knob in single row, extending beyond knob; 2 rows oral shield sclerites indistinct.   
 Etymology: L. cuspidatus -a, -um = pointed.   
 Description: External appearance (Figs. 1A, 2A, B): Nearly transparent, smooth body <3mm long and narrow, junction between trunk and shank clear owing to internal organs seen through transparency of trunk as well as usually by body shape, posterium/trunk length index 0.85–1.30; holotype length 2.4 mm, anterium <0.1 mm, trunk 1.3 x 0.4 mm, shank 0.8 x 0.2 mm, knob 0.3 mm, posterium/trunk index 0.85; oral shield small, often exposed, oral shield sclerites scarcely evident; trunk sclerites at 45º angle to body axis on trunk (Fig. 2A, B), diverging along ventral midline (Fig. 2A), converging along dorsal midline; shank sclerites adpressed, noticeably shorter than on trunk; knob cone-shaped, fringing sclerites in single row extending beyond end of cone.   
 Sclerites (Figs 2F, G, 3, 4A–C): General: anterium through shank with slightly raised, distal, pointed blade, or nipple; base curved toward body (Fig. 3J); from ventral anterium, dorsal trunk, and ventral trunk, sausageshaped, of even width; juveniles as in adults but smaller (Fig. 2G). Beside oral shield (Fig. 3A): asymmetrical, curved, rounded basally and distally, groove indistinct, thin, to 36 x 16 x 2 µm, thickest medially. Dorsal to oral shield (Fig. 3B): grooved thin scales tapered to blunt point, to 30 x 14 x 1 µm. Dorsal and lateral anterium (Fig. 3C): of even width or basally broad, most with distinct, medially offset groove, proximal end angular, to 90 x 18 x 4–5 µm, gradually becoming narrower and thicker ventrally (Fig. 3D), similar to ventral trunk sclerites. Ventral trunk (Fig. 3E): shorter than dorsal trunk, to 80 x 15 µm. Dorsal trunk (Fig. 3F): as in diagnosis, to 120 x 20 x 5 µm, thickest medially beside distinct or indistinct groove. Shank (Fig. 3G): from small sausage-shaped to long and tapered from angular proximal end to distal end, thickest medially, to 140 x 30 x 7 µm. Fringing (Fig. 3I): long, straight, narrow, some with distinct waist, to 190 x 10 µm, most to 4 µm thick but up to 7 µm. Knob (Fig. 3H): short, extremely narrow to somewhat proximally broadened needles, to 90 x 7 x 2 µm.   
 Radula and jaws: 2 examined. Jaws 210 x 75 µm (Fig. 2D); radula teeth 53 µm long, serrated membrane about 30 µm, situated almost in middle of tooth; central plate symmetrical, to 25 µm (Fig. 2E).   
 Distribution: Known only from the continental slope of the Gulf of Mexico between 357 and 1,032 m (Fig. 24A; Table 1).   
 Remarks: Chevroderma cuspidatum inhabits shallower depths than other known Chevroderma species. It is the only Chevroderma species in the Gulf of Mexico. C. cuspidatum may be endemic to the Gulf of Mexico. The closely adpressed, sausage-shaped sclerites with a sharp, distal nipple diverge morphologically from all other Chevroderma sclerites, although a similar morphology occurs in two undescribed Pacific species. In outline they are similar to those of Prochaetoderma? atlanticum Scheltema & Ivanov, but having a groove and chevron-shaped growth lines, as well as the angled base of Chevroderma species on anterium and shank sclerites. We interpret the slightly raised, sharp nipple as all that remains of a blade on these otherwise closely adpressed sclerites (Figs 3J, 4A – C).
description: Published as part of Ivanov, Dmitry L. & Scheltema, Amélie H., 2008, NMR solution structures of KAP- 1 PHD finger-bromodomain, pp. 1-60 in Zootaxa 1885 on pages 6-9, DOI: 10.13018/bmr11036, http://zenodo.org/record/5133706