Prochaetoderma gilrowei 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
Prochaetoderma
Prochaetoderma gilrowei

description: Prochaetoderma gilrowei n. sp.   
(Figures 1G, 16, 17, 18D–F, 24C, 25; Tables 1, 2, 4a)  
 Type material: Holotype USNM 1112619. Paratypes: USNM; TAMU; ZMUM Le1–156 (DGoMCS 4447, station E2b/3); Le1–157 (DGoMB S35/3).   
 Type locality: Gulf of Mexico, 28°15.16'N, 86°25.07'W, 767 m (DGoMB S42/1, 09.06.2000).   
 Material examined: Gulf of Mexico, 159 specimens (Table 1); Guiana Basin, 60 specimens (Table 4a).   
 Diagnosis: Small (<2.0 mm), almost cylindrical, glistening, semi-transparent sclerites closely adpressed on trunk, shank short, fringing sclerites in single row, long, many more than twice length of knob; with short, broad shank, posterium 1/3 to <1/2 trunk length; anterium usually slightly everted; junction of shank and knob clearly demarcated. Oral shield sclerites in 2 rows. Trunk sclerites short, thin, symmetrical, with longitudinal axis straight (most) to curved, sharply pointed distally, with distinct distal keel, waist distinct, blade with sharp, fine longitudinal ridges, base with fine longitudinal striations (Fig. 18F).   
 Etymology: Named in honor of Dr. Gilbert Rowe, who provided us with much of the Gulf of Mexico material reported here.   
 Description: External appearance: Small, to 1.8 mm, many <1.0 mm, almost cylindrical, trunk diameter 0.4–0.5 mm, mid-shank diameter 0.2–0.4 mm, posterium/trunk index varying from 0.33–0.44; holotype length 1.6 mm, anterium 0.1 mm, trunk 1.1 x 0.5 mm, shank 0.2 x 0.4 mm, knob 0.2 mm, posterium/trunk index 0.36;. Oral shield 0.08–0.14 mm in height, sclerites from 4 to 8 in each of 2 rows, those of second row largest (Fig. 16D).   
 Sclerites (Figs 16E, 17, 18D–F): General: Short, thin, symmetrical, less than 170 µm long, 5 µm thick, longitudinal axis to somewhat curved (Figs 17J, 18D, E), waist indented, blade narrower than base, thickest at waist and blade, sides of base convex, of blade straight to convex, proximally rounded, distally sharply pointed; keel on blade with fine, sharp ridges, base striated (Fig. 18D, F). Oral shield (Fig. 17A): straight to curved, tapered basally, thick, to 50 x 15 x 4 µm, thickest proximally. Dorsal to oral shield (Fig. 17B): very thin scales, most sub-triangular, to 45 x 30 x <1 µm. Anterium (Fig. 17C): either short with curved, narrow base, or with distinct waist, blade and base almost equal in length, to 100 x 30 x 3 µm, blade narrower than base. Dorsal trunk (Figs 16E, 17F, 18D, E): as in general description, to 160 x 45 x 5 µm, thickest on keel near waist, blade and base width 30 and 45 µm, respectively. Ventral and lateral trunk (Fig. 17D, E): similar to those from dorsal trunk, but most shorter and narrower. Shank (Fig. 17G): either broad-based with short blade, 110 x 45 µm, or with narrower base and elongate blade, to 160 x 35 µm, both types thickest on blade. Fringing (Fig. 17I): long and slightly curved, to 500 x 8 x 8 µm. Knob (Fig. 17H): curved, tapered at both ends, thickest medially, to 140 x 15 x 4 µm.   
 Radula and jaws: 2 examined. Jaws 310 x 120 µm (Fig. 16F); radula teeth 85 µm long, serrated membrane short, about 40 µm, situated further proximally than distally; central plate asymmetrical, to 35 µm (Fig. 16G).   
 Distribution: Continental slope and uppermost rise: Gulf of Mexico 334–1,032 m (Fig. 24C), Guiana Basin 508 m and 1,000 m (Fig. 25; Tables 1, 2, 4a).   
 Remarks: Prochaetoderma gilrowei is distinguish from other Prochaetoderma species by its short cylindrical body with a short, broad posterium. Mid-trunk sclerites are similar to those of P. yongei Scheltema, 1985 but are ornamented, the blade with longitudinal ridges and the base and waist with longitudinal striations (Fig. 18D, F).
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 26-27, DOI: 10.13018/bmr11036, http://zenodo.org/record/5133706