Claviderma mexicanum, Ivanov & Scheltema, 2008

Ivanov, Dmitry L. & Scheltema, Amélie H., 2008, NMR solution structures of KAP- 1 PHD finger-bromodomain, Zootaxa 1885, pp. 1-60 : 19-22

Claviderma mexicanum n. sp.

( Figures 1F , 11 , 12 , 13F , 24B , 25 , Tables 1, 2, 4a)

Type material: Holotype USNM 1112617 . Paratypes: USNM; TAMU ; ZMUM Le1–170 (DGoMB S36/1).

Type locality: Gulf of Mexico, 27°49.68'N, 89°10.07'W, 1,401 m (DGoMB, MT4 /3, 16.06.2000) .

Material examined: Gulf of Mexico, 42 specimens ( Table 1); Guiana Basin, 14 specimens ( Table 4a) .

Diagnosis: Slender, opaque, to 5.5 mm long, shank width about 1/2 trunk width, long, posterium to 2/3–3/ 4 trunk length, shank demarcated from trunk and knob; trunk but not shank sclerites adpressed, at 45º to longitudinal body axis, sclerites fringing knob in single row, extending beyond knob; knob covered by short sclerites, with two lateral clusters of long, hair-like sclerites, but often missing. Oral shield sclerites in 3 rows. Trunk sclerites straight, symmetrical, base long, thick, narrowest proximally, widest at waist, blade short, sides straight, distally pointed ( Fig. 13F ).

Etymology: L. mexicanus, -a, -um, after type locality.

Description: External appearance ( Figs 1F , 11 A-C): Elongate, slender, 5.5 x 0.75 mm, translucent to opaque, shank long, narrow, posterium/trunk index 0.65–0.75; holotype length 5.2 mm, anterium 0.1 mm, trunk 3.0 x 0.7 mm, shank 1.7 x 0.4 mm, knob 0.4 mm, posterium/trunk index 0.70; trunk sclerites adpressed, diverging clearly from ventral midline, convergent along dorsal midline; shank shaggy, clearly demarcated from smooth trunk and knob, fringing sclerites in single row extending beyond cone-shaped knob. Oral shield 0.25–0.30 mm in height, each of the 3 rows increasing in size to largest dorsally.

Sclerites ( Figs 11G, H , 12 , 13F ): General: without indented waist except anteroventrally, sides straight, base long, narrowest proximally, widest distally, blade short, tapered to sharp point, plane of blade slightly bent outward from plane of base ( Fig. 12F ). Oral shield ( Fig 12A ): nearly straight with rounded, proximal end, tapered to rounded, distal end, thick, to 120 x 45 x 7 µm, thickest medially. Dorsal to oral shield ( Fig. 12B ): thin scales tapered distally, to 60 x 25 x 1 µm, gradually merging with sclerites of anterium. Anterium ( Fig. 12C ): short, either broad without waist, or narrow with waist, distally pointed, thickest medially, to 100 x 20–35 x 4 µm. Dorsal anterium ( Fig. 12 D ): narrow, waist indented or not, base and blade of equal width, thickest on base, to 170 x 30 x 7 µm. Dorsal trunk ( Figs. 12H , 13F ): blade short, <1/6 total length, to 320 x 35 x 10 µm, thickest medially on base. Ventral trunk ( Figs. 12E, G ): either similar to those from dorsal trunk but shorter and of nearly same width, or with indented waist similar to ventral sclerites of anterium, but longer. Shank ( Fig. 12I ): similar to those from dorsal trunk but blade longer and narrower, about 1/4 to 1/3 total length, and base wider proximally, waist indistinct; to 320 x 30 x 9 µm, thickest medially on base. Fringing ( Fig. 12K ): long, straight, narrow, to 600 x 15 x 3 µm. Knob: short, narrow, covering knob, to 5 µm thick ( Fig. 12J ), and, if not broken off and missing, two hair-like lateral groups extending well beyond knob ( Fig. 11H ). Sclerites of juveniles similar to those from adults but shorter with narrower blade.

Radula and jaws: 2 examined. Jaws 540 x 230 µm ( Fig.11F ); radula teeth 130 µm long, serrated membrane about 80 µm, situated medially; central plate curved, to 55 µm ( Fig.11E ).

Distribution: Known from the Gulf of Mexico on the continental slope and rise, 353–1,825 m ( Fig. 24B , Tables 1, 2) and from 1,456 m on the continental rise in the Guiana Basin ( Fig. 25 , Table 4a).

Remarks: Claviderma mexicanum is a slender form with a moderately long posterium; the two lateral clusters of long, hair-like sclerites extending from the knob are distinguishing, if present. The trunk sclerites are long, thick, and unusual in that the waist is defined by the widest part of the sclerite between the short blade and long base.

Figures

FIGURE 1. Holotypes of new Prochaetodermatidae species in the western Atlantic Ocean south of 35°N. A. Chevroderma cuspidatum, Gulf of Mexico. B. Claviderma amplum, Gulf of Mexico. C. Spathoderma compactum, Argentine Basin. D. Claviderma crassum, Guiana Basin. E. Spathoderma bulbosum, Gulf of Mexico. F. Claviderma mexicanum, Gulf of Mexico. G. Prochaetoderma gilrowei, Gulf of Mexico. H. Niteomica captainkiddae, Gulf of Mexico. I. Spathoderma quadratum, Gulf of Mexico.

FIGURE 11. Claviderma mexicanum n. sp., Gulf of Mexico. A, G. Holotype (DGoMB, MT4/3). B–F. Paratypes (C is juvenile) (DGoMB, S36/1). A–C. Entire. D. Oral shield sclerites in situ. E. Radula teeth and central plate. F. Jaw. G. Mid-trunk sclerites. H. Sclerites from different body regions, juvenile.

FIGURE 12. Claviderma mexicanum n. sp., sclerites from same paratype as Figure 11B. A. Oral shield. B. Dorsal to oral shield and dorsal anterium. C. Lateral anterium. D. Dorsal anterium. E–G. Ventral trunk (F, lateral view). H. Dorsal and lateral mid-trunk. I. Shank. J. Knob. K. Fringe.

FIGURE 13. Trunk sclerites of Claviderma n. spp. paratypes (SEM). A, B. Cl. compactum, Argentine Basin, type locality; B showing fine striations not visible in A and subtriangular cross-section of thick sclerite. C–E. Cl. crassum, Guiana Basin, type locality; C, E showing long blade and sharp striations, enlarged in D; E showing curved sclerite. F. Cl. mexicanum, Gulf of Mexico, type locality; sclerites as they appear in situ.

FIGURE 24. A–C. Distribution of Prochaetodermatidae species in the Gulf of Mexico. Stations without prochaetodermatid species indicated by small black circles.

FIGURE 25. Distribution of Prochaetodermatidae species outside the Gulf of Mexico but restricted to the western Atlantic south of 35ºN.