Anchimolgus pandus Humes 1978

Anchimolgus pandus

TYPE MATERIAL.—6 , 4 from one Fungia (Ctenactis) echinata (Pallas), in 3 m, southwestern side of Goenoeng Api, Banda Islands, 4°31′45″S, 129°51′55″E, 25 May 1975. Holotype , allotype, and 6 paratypes (4 , 2 ) deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C.; the remaining paratypes (dissected) in the collection of the author.

OTHER SPECIMENS.—From Fungia echinata: 2 from one host, in 5 m, Poelau Gomumu, south of Obi, Moluccas, 1°50′00″S, 127°30′54″E, 30 May 1975.

From Fungia (Pleuractis) paumotuensis Stutchbury: 1 from two hosts, in 2 m, Poelau Naira, Banda Islands, 4°31′45″S, 129°53′35″E, 2 May 1975.

From Fungia (Heliofungia) actiniformis (Quoy and Gaimard): 1 from eight hosts, in 3 m, Natsepa, Ambon, 3°37′05″S, 128°17′00″E, 24 April 1975.

From Polyphyllia talpina (Lamarck): 2 from one host, in 10 m, southern shore of Goenoeng Api, Banda Islands, 4°32′05″S, 129°51′30″E, 26 April 1975.

FEMALE.—Body (Figure 7a) with flattened and moderately broad prosome. Length 1.27 mm (1.23–1.31 mm) and greatest width 0.55 mm (0.53–0.57 mm), based on 6 specimens. Ratio of length to width of prosome 1.39:1. Ratio of length of prosome to that of urosome 1.57:1.

Segment of leg 5 (Figure 7b) 78 × 198. Genital segment 180 × 180, in dorsal view moderately broadened in anterior two-thirds with irregular margins. Genital areas located dorsolaterally just posterior to middle of segment. Each area (Figure 7c) with two naked setae 11 and 22 and a small spiniform process. Postgenital segments from anterior to posterior 65 × 91, 55 × 86, and 91 × 99. Posteroventral margin of anal segment with row of small spinules on both sides.

Caudal ramus (Figure 7d) 101 × 48, approximately two times longer than wide. Outer lateral seta 240, dorsal seta 65, outermost terminal seta 154, innermost terminal seta 264, and two long median terminal setae 418 (outer) and 440 (inner), both inserted between small, smooth dorsal flange and ventral flange with minute marginal spinules. All setae with lateral hairs except naked dorsal seta.

Body surface with sparse hairs (sensilla) as in Figure 7a.

Egg sac (Figure 7e) elongated, 500 × 108, containing about 12 eggs 96–125 in diameter.

Rostrum (Figure 7f) with incomplete dorsoventral edge. First antenna (Figure 7g) 549 long. Lengths of seven segments: 47 (86 along anterior margin), 170, 40, 114, 63, 50, and 26 respectively. Setation as in Anchimolgus notatus. All setae naked.

Second antenna (Figure 7h) 265 long. Formula as in A. notatus, but setae on first two segments minute and often difficult to see. Fourth segment short, 41 along outer side, 22 along inner side, and 18 wide. Claw (Figure 7i) 44 along axis, with distinctly bent tip.

Labrum (Figure 7j) with two broad posteroventral lobes. Mandible (Figure 8a) and paragnath (Figure 7j) and first maxilla resembling those of Anchimolgus latens. Second maxilla (Figure 8b) with inner seta on second segment having spinules on both sides about equal in length. Proximalmost spine on lash stouter than succeeding spine. Maxilliped (Figure 8c) resembling in general that of A. notatus.

Ventral area between maxillipeds and first pair of legs (Figure 8d) resembling that of A. notatus and A. latens.

Legs 1–4 (Figure 8e–h) segmented and armed as in A. notatus. Coxa of leg 1 with rounded lobe on outer posterior surface. Exopod of leg 1 with proximal outer spine on third segment noticeably longer (39) than two adjacent spines (33 and 32). In legs 2 and 3 these spines nearly equal in length. Leg 4 with small naked coxal seta 10. Exopod 180. First segment of endopod 31 long including spiniform processes (29 without those processes) and 23 wide, inner distal plumose seta 65. Second segment 65 with spiniform processes (61 without processes) and 19 in greatest width (15.5 in least width); two terminal fringed spines 34 (outer) and 65 (inner). Outer margins of both segments with hairs and proximal inner margin of second segment with short spinules.

Leg 5 (Figure 8i) with long free segment 107, its greatest width at proximal inner expansion 32, its least width distally 17. Two terminal naked setae 82 and 60. Segment bearing small spines along outer surface. Dorsal seta 75 and naked.

Leg 6 represented by two setae on genital area (Figure 7c).

Living specimens colored as in A. notatus.

MALE.—Body (Figure 9a) with moderately broad prosome. Length 1.07 mm (1.05-1.10 mm) and greatest width 0.41 mm (0.40–0.42 mm), based on 4 specimens. Ratio of length to width of prosome 1.41:1. Ratio of length of prosome to that of urosome 1.52:1.

Segment of leg 5 (Figure 9b) 44 × 135. Genital segment in dorsal view 229 × 221 (length including leg 6), approximately as long as wide. Four postgenital segments from anterior to posterior 31 × 72, 39 × 69, 32 × 70, and 60 × 86.

Caudal ramus similar to that of female, but smaller, 81 × 42, with ratio of 1.93:1.

Rostrum like that of female. First antenna similar to that of female, but three long aesthetes added (at points indicated by round dots in Figure 7g) as in two previous species.

Second antenna (Figure 9c) like that of female but inner surfaces of second and third segments with small hyaline spines.

Labrum, mandible, paragnath, first maxilla, and second maxilla resembling those of female. Maxilliped (Figure 9d) similar in most respects to that of A. latens. Claw 212 along axis.

Ventral area between maxillipeds and first pair of legs like that of female.

Leg 1 with endopod formula 0–1; 0–1; I, I, 4 (Figure 9e), but otherwise resembling that of female. Legs 2–4 like those in female.

Leg 5 (Figure 9f) with free segment 38 × 10.5, two terminal elements 26 and 39.

Leg 6 (Figure 9g) a posteroventral flap on genital segment bearing two naked setae 20 and 25.

Spermatophore (Figure 9h) 200 × 94 not including neck, attached to female in pairs.

Living specimens colored as in A. notatus.

ETYMOLOGY.—The specific name pandus (Latin, = bent or crooked) alludes to the bent tip on the claw of the second antenna.

COMPARISON WITH OTHER SPECIES OF Anchimolgus.—The claw of the second antenna in Anchimolgus pandus is unlike that of all other species in the genus in having a distinctly bent tip. This feature, observable without dissection, serves as a good recognition character for the new species.

The greater length of the proximal outer spine on the third segment of the exopod of leg 1 is also characteristic of A. pandus. In all other species the outer spines on the exopod of leg 1 are of nearly equal length. The formula III, I, 5 on the third exopod segment of leg 4 is a further distinctive feature of the new species.