Spathoderma quadratum, Ivanov & Scheltema, 2008

Ivanov, Dmitry L. & Scheltema, Amélie H., 2008, NMR solution structures of KAP- 1 PHD finger-bromodomain, Zootaxa 1885, pp. 1-60 : 33-44

publication ID	https://doi.org/ 10.13018/bmr11036
persistent identifier	https://treatment.plazi.org/id/3076EC0B-FFA1-FFA6-5DAB-FBDCFEC908CD
treatment provided by	Felipe
scientific name	Spathoderma quadratum
status	sp. nov.

Treatment

Spathoderma quadratum View in CoL n. sp.

( Figures 1I View FIGURE 1 , 21 View FIGURE 21 , 22 View FIGURE 22 , 23C, D View FIGURE 23 , 24A View FIGURE 24 , 25 View FIGURE 25 ; Tables 1, 2)

Type material: Holotype USNM 1112618 View Materials . Paratypes: USNM; TAMU ; ZMUM Le1–162 (DGoMB stn RW2 / 3) ; Le1–163 (DGoMB stn S36/2).

Type locality: Gulf of Mexico, 28°55.16'N, 87°40.22'W, 1,825 m (DGoMB, S36/1, 12.06.2000) GoogleMaps .

Material examined: Gulf of Mexico, 38 specimens ( Table 1) .

Diagnosis: Small, length to 2.3 mm, trunk opaque, anterior end widest, body tapering to posterior end, posterium about 1/2 trunk length; trunk and shank poorly demarcated; sclerites arranged almost parallel to body axis; knob bulb-shaped, junction of shank and knob clearly demarcated, fringing sclerites in single row, extending well beyond knob. Oral shield sclerites in 3 rows. Trunk sclerites large, thick, base broad and quadrate, length of blade increasing posteriorly from less than to greater than length of base.

Etymology: L. quadratus, -a, -um = having four corners.

Description: External appearance ( Figs 1I View FIGURE 1 , 21A View FIGURE 21 ): Small, to 2.3 x 0.6 mm, opaque, widest anteriorly, tapered from anterior end to knob, shank indistinct from trunk, scleriters arranged nearly parallel to body axis, knob ending in rounded point; posterium/trunk index ranging from 0.50–0.60; holotype length 2.2 mm, anterium <0.1 mm, trunk 1.4. x 0.5 mm, shank 0.5 x 0.25 mm, knob 0.3 mm, posterium/trunk index 0.57; Oral shield 1.2–1.5 mm in height, oral shield sclerites increasing greatly from inner to outer 3 rd row and from ventral to dorsal ( Fig. 21B View FIGURE 21 ). Sclerites ( Figs. 21E View FIGURE 21 , 22 View FIGURE 22 , 23C, D View FIGURE 23 ): General: Sclerites large, thick, long axis straight except anteriorly, waist distinct, base wide, quadrate, blade bent outward from body ( Fig. 22K View FIGURE 22 ), increasing in length from shorter than base anteriorly to longer than base posteriorly, distal end sharply pointed ( Figs 22 View FIGURE 22 , 23C View FIGURE 23 ); base with fine, smooth, irregular longitudinal striations ( Fig. 23D View FIGURE 23 ). Oral shield ( Fig. 22A View FIGURE 22 ): ovoid, straight, or one side concave, without distal point, thick, to 60 x 30 x> 7 µm, thickest proximally. Dorsal to oral shield ( Fig.22B View FIGURE 22 ): thin and flame-shaped, to 70 x 25 x 3 µm. Anterium ( Fig. 22C, D View FIGURE 22 ): short, broad, with waist and short blade less than 1/3 total length, to 130 x 45 x> 5 µm, thickest at mid-base, or base and blade narrow with distinct waist, to115 x 30 x> 5 µm. Anterior trunk ( Fig. 22E View FIGURE 22 ): base not quadrate, rounded proximally, sides convex, blade length only slightly less than base length, base proximally rounded, 200 x 45 x 7 µm. Dorsal trunk ( Fig. 22G View FIGURE 22 ): as in general description, base with parallel sides at right angles to proximal flat or rounded end, blade shorter to slightly longer than base, to 300 x 95 x 9 µm, symmetrically thickened, thickest medially on base. Ventral mid-trunk ( Fig. 22F View FIGURE 22 ): similar to those from dorsal trunk, but most somewhat shorter and narrower, quadrate, bent at waist, to 240 x 70 x 9 µm. Shank ( Fig. 22H View FIGURE 22 ): similar to those of dorsal trunk but with long blade up to twice base length, waist distinct, to 410 x 65 x 9 µm, thickest medially on base or on blade, some shank sclerites with ovoid base and short blades. Fringing ( Fig. 22J View FIGURE 22 ): long, straight, narrow, waist distinct, base quadrate, to 420 x 60 x 9, thickest on mid-blade. Knob ( Fig. 22I View FIGURE 22 ): straight or curved, tapered at both ends, or narrow needles,>200 x 20 x 7 µm.

Radula and jaws: 1 examined. Jaws 495 x 200 µm ( Fig. 21C View FIGURE 21 ); radula teeth 105 µm long, serrated membrane about 40 µm, situated almost medially; central plate straight, somewhat asymmetrical, to 30 µm ( Fig. 21D View FIGURE 21 ).

Distribution: Known only from Gulf of Mexico on the continental slope and rise, 547–1,832 m ( Fig. View FIGURE 24

24A; Table 1).

Remarks: S. quadratum closely resembles the body shape of S. bulbosum , and of sclerites as juveniles. The characters that distinguish them are: in S. quadratum there is a distinct single ring of long, fringing sclerites (sometimes broken off) between the shank and knob extending well beyond the knob; and in S. bulbosum the fringing sclerites are not distinct from the shank sclerites and there are instead groups of long sclerites arising from the knob (also sometimes broken off). Differences in the bases of dorsal trunk sclerites are: rounded basally in S. bulbosum , thickest medially at waist, and to 60 µm wide; and straight basally in S. quadratum , thickest medially below waist, and to 95 µm wide. Although the depth ranges of these two species overlap in the Gulf of Mexico, S. quadratum was collected from shallower depths, with the shallowest and deepest depths of 247 and 1,832 m, respectively; and S. bulbosum occurred at greater depths, between 622 and 3,000 m. The geographic ranges also differ, with S. quadratum restricted to the Gulf of Mexico and S. bulbosum extending outside of the Gulf of Mexico from off the coast of North Carolina to the Guiana Basin and off Recife, Brazil.

The quadrate shape of dorsal trunk sclerites distinguishes S. quadratum from all other described Atlantic Spathoderma species , although they bear some resemblance to the those of S. grossum . The sclerites of S. quadratum are thickest on the base, those of S. grossum on the blade, and the two species do not overlap in depth or geographic range.

1 Specimens lost.

2 Deposited in ZMUM.

3 Specimens lost, with the exception of paratypes deposited in ZMUM .

4 Deposited in TAMU. For Ch. cuspidatum, MT 3/1, 3 specimens from type locality.

Species abbreviations: Ch. cusp. = Chevroderma cuspidatum, Sp. bulb. = Spathoderma bulbosum, Sp. quad. = S. quadratum, Cl. amp. = Claviderma amplum, Cl. mex. = Claviderma mexicanum, Pr. gilr. = Prochaetoderma gilrowei, Nit. capt. = Niteomica captainkiddae . All are sp. nov.

*Endemic species.