Pseudanthessius major Stock 1967

Pseudanthessius major Stock, 1967

SPECIMENS COLLECTED.—2 , 2 from one crinoid, Himerometra magnipinna A. H. Clark, in an intertidal pool, Ricaudy Reef, near Noumea, New Caledonia, 22°19′00″S, 166°26′44″E, 10 July 1971; 30 , 32 , 2 copepodids from one crinoid, Stephanometra spicata (P. H. Carpenter), in 3 m, eastern end of Isle Maître, near Noumea, 22°20′35″S, 166°25′45″E, 8 June 1971.

Pseudanthessius major Stock, 1967

Nearly 900 specimens of this copepod, thus far known only from the Red Sea, have been collected in Madagascar from six different crinoids, as follows:

From Cenometra emendatrix (Bell): 43 , 42 , and 23 copepodids from 5 hosts, in 20 m, south of Tany Kely, a small island to the south of Nosy Bé, 10 September 1963; 49 , 24 , and 13 copepodids from 6 hosts, in 20 m, south of Tany Kely, 11 October 1963; 23 , 6 , and 1 copepodid from 2 hosts, in 20 m, south of Tany Kely, October 1963; 19 , 12 from 2 hosts, in 10 m, northwestern coast of Nosy Ovy (=Berafia), Isles Radama, 13°59′00″S, 47°46′30″E, 1 October 1964; and 66 , 33 and 1 copepodid from 11 hosts, in 20 m, Banc de Dzamandzar, western coast of Nosy Bé 30 August 1967.

From Heterometra africana (A. H. Clark): 4 , 8 and 4 copepodids from 1 host, on sand in 18 m, in pass between Nosy Bé and Nosy Komba at Pte. Lokobe, 14 July 1967; 48 , 32 , and 17 copepodids from 1 host, on shell fragment on sandy bottom in 34 m, 1 km south of crater near Ambatoloaka, Nosy Bé, 24 July 1967; 7 from 1 host, in 25 m, trawl 13°29′30″S, 48°02′00″E to 13°28′00″S, 48°02′30″E, southwest of Nosy Bé, 11 August 1967; 1 , 2 from 1 host, on sand in 17 m, in pass off Pte. Lokobe, 15 August 1967; 13 , 20 , and 73 copepodids from 1 host, on octocoral on sandy bottom in 29 m, 1 km south of crater near Ambatoloaka, 21 August 1967; 2 , 1 from 1 host, on sand in 17 m, in pass between Nosy Bé, and Nosy Komba, 16 August 1967; 46 , 18 from 1 host, in 17 m, in pass off Pte. Lokobe, 23 August 1967; 24 , 14 , and 5 copepodids from 3 hosts, on sand in 17 m, in pass off Pte. Lokobe, 27 August 1967; and 47 , 20 , and 10 copepodids from 4 hosts, in 18 m, near black buoy north of Nosy Varona, a small island almost between Nosy Bé, and Nosy Komba, 30 August 1967.

From Stephanometra indica (Smith): 1 , 2 from host, in 2 m, Antsiabe, on southern shore of Nosy Komba, 8 July 1967; 20 , 17 from 1 host, in 17 m, in pass off Pte. Lokobe, 16 August 1967; and 2 from 1 host, on sand in 13 m, opposite Antisabe, 2 September 1967.

From Lamprometra klunzingeri (Hardaub): 2 , 1 from 1 host, in 1 m, Pte. Ambarionaomby, Nosy Komba, 3 September 1963; and 1 , 4 , and 2 copepodids from 1 host, on sand in 13 m, opposite Antsiabe, 2 September 1967.

From Liparometra? sp.: 4 , 1 from 1 host, on sand in 15 m, in pass off Pte. Lokobe, 13 June 1967; 3 , 1 from 1 host, in 27–23 m, trawl 13°29′S, 48°09′E to 13°28.5′S, 48°11.5′E, south of Nosy Bé, 11 August 1967; and 3 , l from 1 host, in 35m, trawl 13°26.1′S, 48°11.7′E to 13°25.5′S, 48°11′E, south of Nosy B6, 24 August 1967.

From Dichrometra sp.? afra A. H. Clark: 3 , 1 from 1 host, in 2 m, Pte. Lokobe, 2 September 1960; 13 , 3 from 1 host, in 1 m, west of Pte. Mahatsinjo, Nosy Bé, 2 November 1960; 4 , 3 from 1 host, in 6 m, Ambariobe, a small island almost between Nosy Bé and Nosy Komba, 28 December 1963; and 16 , 13 from 1 host, in 2 m, Ambariotelo, a small island near Ambariobe, 24 May 1964.

Specimens have been deposited in the United States National Museum and in the Zoölogisch Museum, Amsterdam.

Although the Madasgascan specimens are readily determinable from Stock’s original description, we take this opportunity to add certain information, based upon specimens from Cenometra emendatrix unless otherwise noted. Structures not mentioned may be assumed to be essentially as described by Stock.

FEMALE.—Length of body (Figure 29) 0.85 mm (0.79–0.88 mm) and greatest width 0.45 mm (0.43–0.47 mm), based on ten specimens. Ratio of length to width of prosome, 1.43:1. Ratio of length of prosome to that of urosome, 2:1.

Segment of leg 5, 60 × 96μ. Between this segment and genital segment a short and rather weak ventral intersegmental sclerite. Genital segment 112 × 122μ, with its shape in all specimens like that shown in Stock’s figure 7a rather than like that in his figure 7b. Attachment area of each egg sac bearing two naked setae (18μ and 13μ long) and a spiniform process (Figure 30). Three postgenital segments, 34 × 69μ, 28 × 62μ, and 30 × 58μ, from anterior to posterior.

Caudal ramus (Figure 31) 22 × 20μ, including terminal ventral flange which bears a row of minute spinules. Outer lateral seta 45μ, dorsal seta 25μ, and outermost terminal seta 74μ, all three of them naked. Innermost terminal seta 110μ, with spinules along its inner edge. Two median terminal setae (275μ, outer, and 400μ, inner), both with lateral spinules.

Egg sac (Figure 29) elongated (in specimen drawn, 638 × 187μ) and having about 90 eggs, each approximately 62μ in diameter. In a female from Liparometra, each sac containing about 55 eggs; and in one from Stephanometra, about 40 eggs.

Rostrum (Figure 32) weakly developed and often showing, to varying degrees, a small median sclerotized knoblike area.

First antenna 250μ long, lengths of its segments being 28 (50μ along its anterior margin), 64, 20, 42, 38, 23, and 13μ, respectively. Third segment with six setae (rather than five as described by Stock). All setae naked.

Last segment of second antenna 44μ along inner edge, 75μ along outer edge, and 19μ wide. Terminal claws 28μ and 19μ, measured along their axes.

Labrum (Figure 33) with two divergent posteroventral lobes.

Mandible having on its convex edge a scale more prominent than that illustrated by Stock in his figure 8b, and more like mandible of P. madrasensis shown in our Figure 10. Paragnath a small lobe with a few hairs. Maxilliped (Figure 34) with two setae on second segment, and number of denticles on spine and on spiniform prolongation of third segment varying from none to four.

Ventral area between maxillipeds and first pair of legs (Figure 35) only slightly protuberant. A fine line connecting bases of maxillipeds.

Curved spine on last segment of endopod of leg 1 (Figure 36) finely barbed. Exopod of leg 4, 130μ long, and endopod 60μ (including terminal spiniform process) × 18μ, with its two terminal elements 47μ (outer) and 71μ (inner).

Leg 5 (Figure 37) with a dorsal seta (30μ) and two unequal posterolateral setae, one stout and 108μ, the other more slender and 44μ All three setae naked.

Color in life in transmitted light translucent to slightly opaque, eye red, egg sacs gray.

MALE.—Length of body (Figure 38) 0.67 mm (0.65–0.70 mm) and greatest width 0.30 mm (0.29–0.31 mm), based on ten specimens. Ratio of length to width of prosome, 1.45:1. Ratio of length of prosome to that of urosome, 1.79:1.

Segment of leg 5, 25 × 47μ Between this segment and genital segment no distinct ventral intersegmental sclerite. Genital segment 88 × 79μ Four postgenital segments, 27 × 43μ, 20 × 40μ, 15.5 × 36μ and 17.5 × 36μ, from anterior to posterior. Anal segment as in female bearing on each side a posteroventral row of spinules (more than four in number as in Stock’s description).

Caudal ramus 17 × 16.5μ and similar to that of female.

Claw of maxilliped (Figure 39) 90μ along its axis, weakly divided near its middle, bearing two unequal setae proximally.

Last segment of endopod of leg 1 (Figure 40) showing fairly strong sexual dimorphism. Outer spine 22μ and prominently barbed. Length of segment, 26.5μ, with ratio of spine to segment 1:1.2. Two outermost setae stouter than other three; near their insertions an antero-inwardly directed spinous process bearing spinules. In specimens from Dichrometra, Stephanometra, Heterometra, Lamprometra, and Liparometra outer spine 14μ with much smaller barbules, and length of segment 24μ, with ratio 1:1.7.

Last segment of endopod of leg 2 usually a with naked outer proximal spine, but in a male from Cenometra this spine barbed in right leg (Figure 41) but smooth in left leg. Length of this segment 40μ and three spines 17, 28, and 46μ from proximal to distal.

Last segment of endopod of leg 3 (Figure 42) with a naked inner terminal spine in all specimens except in a male (from Dichrometra) where it is very slightly barbed.

Leg 5 like that of female except that two posterolateral setae are more equal.

Leg 6 (Figure 43) consisting of a posteroventral flap on genital segment, bearing two naked setae (15μ and 36μ) and a small spinous process.

Spermatophore (Figure 44) attached to female in pairs, about 85 × 42μ, not including neck.

Color in life similar to that of female.

Gulf of Aqaba, Israel; Nosy Be, Madagascar