Neotanais vemae Gardiner 1975

Neotanais vemae

DIAGNOSIS.—Stages Other Than Copulatory Male (copulatory males unknown): *Chela bearing very long, slender dactylus, longer than fixed finger; *propodus with shallow keels dorsally and ventrolaterally on fixed finger; distal propodal teeth very irregular. *Pleotelson long, with rounded posterior margin; *uropods borne posterior to midlateral point. *Pereonites 4–6 generally square in dorsal view, but areas over pereopods expanded laterally. *Pleonites generally rounded midventrally in lateral view. *Carapace laterally compressed, chelipedal coxae poorly expanded laterally in dorsal view; a single anterolateral and posterolateral seta present.

DESCRIPTION OF PREPARATORY FEMALE 1 HOLOTYPE.—Body (Figure 42A): 7.0 mm long and 7.1 times longer than wide.

Carapace: Bearing a single short anterolateral seta and a similar posterolateral seta. Anterolateral keels prominent; rostrum prominent, blunt, and with margin of carapace concave on either side. Respiratory chambers poorly developed and chelipedal coxae flattened laterally in dorsal view, giving carapace a narrow appearance. Oblique furrows modest.

Pereonites (Figure 42B): Pereonites 4–6 generally square in dorsal view, but area above pereopods swollen laterally. Pereonite 5, 1.3 times wider than long.

Pleonites (Figure 42A,D): Rounded laterally in dorsal view and curving posteriorly on either side. Single short hairs located dorsolaterally. Sternites low and variously rounded midventrally.

Pleotelson (Figure 42C,D): Long, 1.5 times wider than long. Posterior border evenly convex except for wide anal area containing small middorsal posterior convexity. Uropods borne posterior to midlateral point.

First Antenna: First article slender, 4.8 times longer than wide. Shapes of articles very similar to those of Neotanais affinis (Figure 39H).

Right Mandible (Figure 42E): Incisive spines 1 and 2 serrate on both sides, the second spine along distal one-third only. Third spine with an irregular tip.

Left Mandible (Figure 42F): Incisive spines as on right side. Lacinia mobilis apparently bearing 3 rounded teeth, the first of which is subdivided into 3 smaller, round teeth; posterior lobe only slightly divided.

Second Maxilla: Fixed endite with 2 stout bifid spines. Medial row containing 11 setae and 2 sharply pointed spines.

Maxilliped: Setal formula of palp, (1,0,5+1,6,13). Left endite with only 2 medial filter setae; 3 on right side.

Cheliped (Figure 42G–I). Dactylus longer than propodus and bearing about 5 or 6 low, flattened, and irregular teeth. Propodal teeth very irregular; proximal area of propodal cutting edge containing irregular denticles. Carpus bearing about 6 short dorsal setae; a prominent ventral convexity located at articulation with merus.

Pereopods II–IV (Figure 43A): Setae slender, apparently smooth; those in anterior rows shorter and stouter than those in posterior rows. Setal formulae, (2,4,5,4), (5,8,6,9), and (6,9,6,8) respectively. Two long, terminal propodal spines bearing relatively large teeth on each leg. Short, terminal propodal spine almost straight and bearing about 9 similarly shaped teeth. Short, subterminal carpal spines (2 in number) straight and naked. (Presence of 2 such spines probably aberrant.)

Pereopods V–VII (Figure 43B–D): Short, subterminal propodal spines on pereopod VII 9 in number and bearing fine setules. Dactyli of pereopods V and VI with large terminal teeth; dactylus of pereopod VII with fine teeth.

Pleopods (Figure 43E): Terminal endopodal setae 1.5 times the length of endopod, thus showing considerable development. Setal formula, (2,1) (3,6,7) (0,2;0,9,4).

Uropods (Figures 42A,C): Similar to those of Neotanais affinis; 9 articles in right endopod, left side missing. Exopod long, 1.1 times the length of first endopodal article.

COMPARISONS.—Significant Differences between Neotanais vemae and N. affinis: (1) The body of vemae is much more slender and delicate and its length-width ratio is 7.1 compared to 6.1 for affinis. (2) Pereonites 4–6 are much more nearly square than in affinis. (3) The uropods are attached more posteriorly in vemae and perhaps slightly more dorsally than South Atlantic specimens of affinis. (4) The carapace is laterally compressed in dorsal view in the area of the chelipedal attachment in vemae. (5) The numbers of propodal and carpal setae of pereopods II–IV are considerably less in vemae than in affinis. (6) The dorsal and ventral keels on the chela are less prominent in vemae.

MATERIAL.—Vema Sta. 15–84, off Chile 5657 m, I P 1 holotype.

LOCATION OF MATERIAL.—AMNH: Holotype (AMNH 14975).

DERIVATION OF NAME.—From R/V Vema of the Lamont Doherty Geological Observatory of Columbia University.