Anchimolgus notatus Humes 1978

Anchimolgus notatus

TYPE MATERIAL.—149 , 354 , and 315 copepodids from two fungiid corals, Fungia (Heliofungia) actiniformis (Quoy and Gaimard), in 2 m, southern end of Poelau Naira, Banda Islands, 4°31′45″S, 129°53′35″E, 2 May 1975. Holotype , allotype, and 495 paratypes (145 , 350 ) deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C.; the remaining paratypes (dissected) and the copepodids in the collection of the author.

OTHER SPECIMENS.—From Fungia actiniformis: 27 , 31 , and 3 copepodids from 8 hosts, in 3 m, Natsepa, Ambon, 3°37′05″S, 128°17′00″E, 24 April 1975.

From Fungia (Pleuractis) paumotuensis Stutchbury: 4 , 12 from 2 hosts, in 2 m, Poelau Naira, Banda Islands, 4°31′45″S, 129°53′35″E, 2 May 1975.

FEMALE.—Body (Figure 1a) with moderately broad and flattened prosome. Length 1.40 mm (1.36–1.43 mm) and greatest width 0.66 mm (0.61–0.68 mm), based on 10 specimens. Epimera of segments of legs 1–3 pointed posteriorly but those of segment of leg 4 rounded. Ratio of length to width of prosome 1.46: 1. Ratio of length of prosome to that of urosome 2.13:1.

Segment of leg 5 (Figure 1b) 78 × 224. Genital segment in dorsal view 198 long, 185 wide in its slightly expanded anterior three-fourths where the sides are nearly parallel, and 127 wide in its posterior fourth. Genital areas situated dorsolaterally near middle of segment. Each area (Figure 1c) with two small naked setae 9 long and a minute spiniform process. Three postgenital segments from anterior to posterior 60 × 112, 47 × 104, and 47 × 101. Posteroventral margin of anal segment with row of minute spinules on both sides.

Caudal ramus (Figure 1d) short, 73 × 48, with ratio of 1.5: 1. Outer lateral seta 91, dorsal seta 90, outermost terminal seta 213, innermost terminal seta 247, and two median terminal setae 352 (outer) and 396 (inner), both somewhat swollen and inserted between smooth dorsal flange and ventral flange with minute marginal spinules. Dorsal seta sparsely haired, but remaining setae with many long hairs.

Body surface with a few small hairs (sensilla) as in Figure 1a.

Egg sac (Figure 1a) 462 × 231, containing approximately 25 eggs about 91 in average diameter.

Rostrum (Figure 1e) broadly rounded. First antenna (Figure 1f) 609 long. Lengths of seven segments 36 (91 along anterior margin), 156, 39, 153, 86, 60, and 24 respectively. Formula: 4, 13, 6, 3, 4 + 1 aesthete, 2 + 1 aesthete, and 7 + 1 aesthete. Long seta on distal anterior corner of second segment swollen proximally (Figure 1g). All setae naked except four on last segment, which are lightly feathered.

Second antenna (Figure 1h) 423 long. First and second segments with minute inner seta. Third segment with three small inner distal setae. Fourth segment 81 along outer edge, 49 along inner edge, and 23 wide. Claw 58 along axis. A minute setule near insertion of claw.

Labrum (Figure 1i) with two broad posteroventral lobes. Mandible (Figure 2a) having on convex side two digitiform processes followed by serrated fringe and bearing on concave side two lobes with long spinules; lash moderately short with spinules. Paragnath (Figure 1i) a small lobe with hairs. First maxilla (Figure 2b) with four setae. Second maxilla (Figure 2c) with a few hairs on distal outer posterior surface of first segment; second segment with inner seta bearing spinules on both sides. Maxilliped (Figure 2d) with second segment having two small naked setae; small third segment with two setae and terminating in sharply pointed process.

Ventral area between maxillipeds and first pair of legs (Figure 2e) not protuberant.

Legs 1–4 (Figure 2f–i) with 3-segmented rami except for endopod of leg 4, which is 2-segmented. Formula for armature (Roman numerals indicating spines, Arabic numerals representing setae):

Coxa of leg 1 with rounded lobe on outer posterior surface. Third segment of endopod of legs 2 and 3 with outer spine nearly twice length of two terminal spines. Leg 4 with inner coxal seta small, 7.5, and naked. Exopod 175. First segment of endopod 17.5 × 14, with distal inner feathered seta 78. Second segment 78 × 12, with two terminal fringed spines 19 (outer) and 42 (inner). Both endopod segments haired along outer margins.

Leg 5 (Figure 2k) with long slender free segment having slight inner proximal expansion and slight notch on outer margin; length 167, width at expansion 29, and width distally 21. Two terminal naked setae 65 and 57. Segment ornamented with small spines along outer surface. Dorsal seta naked and 101. A few spinules on corner of body segment. In one female leg 5 shorter and wider, 130 × 31 (Figure 2j).

Leg 6 represented by two setae on genital area (Figure 1c).

Living specimens in transmitted light opaque, eye red, egg sacs gray.

MALE.—Body (Figure 3a) a little more slender than that of female. Length 1.26 mm (1.19–1.37 mm) and greatest width 0.49 mm (0.45–0.55 mm), based on 10 specimens. Ratio of length to width of prosome 1.48: 1. Ratio of length of prosome to that of urosome 1.40: 1.

Segment of leg 5 (Figure 3b) 55 × 164. Genital segment slightly longer than wide, 286 × 253 (length including leg 6). Four postgenital segments from anterior to posterior 42 × 86, 42 × 91, 34 × 94, and 47 × 94.

Caudal ramus similar to that of female, but smaller, 57 × 44, with ratio of 1.30: 1.

Rostrum like that of female. First antenna resembling that of female, but three long aesthetes added (at points indicated by round dots in Figure 1f). Formula: 4, 13 + 2 aesthetes, 6, 3 + 1 aesthete, 4 + 1 aesthete, 2 + 1 aesthete, and 7 + 1 aesthete.

Second antenna (Figure 3c) differing from that of female in having small spines on inner surfaces of segments 1–3.

Labrum, mandible, paragnath, first maxilla, and second maxilla like those of female. Maxilliped (Figure 3d, e) with first segment having distinct knoblike process on outer surface. Second segment with two naked setae (one of them swollen proximally as in Figure 3f) and a row of spines. Small third segment unarmed. Claw 300 along axis (including large terminal lamella), divided in midregion, and having two unequal proximal setae, longer seta distally bent with small spinules along one side.

Ventral area between maxillipeds and first pair of legs similar to that in female.

Leg 1 with endopod formula 0–1; 0–1; II, 4 (Figure 3g), but otherwise as in female. Legs 2–4 like those of female.

Leg 5 (Figure 3h) with free segment 73 × 12.5, shorter than in female and without marginal notch. Two terminal setae 15 (inner) and 44 (outer.)

Leg 6 (Figure 3i) a posteroventral flap on genital segment bearing two naked setae about 47.

Spermatophore not observed.

Living specimens with color similar to that of female.

ETYMOLOGY.—The specific name notatus (Latin, = marked or distinguished) alludes to the various small but distinctive features of this species.

COMPARISON WITH OTHER SPECIES OF Anchimolgus.—Until now three species of Anchimolgus have been known, all from scleractinian corals. These species are: Anchimolgus digitatus (Humes and Ho, 1968) from Goniopora in Madagascar, Anchimolgus prolixipes (Humes and Ho, 1968) from Porites in Madagascar, and Anchimolgus tener Humes, 1973, from Fungia in New Caledonia.

Anchimolgus notatus may be distinguished from all three known species by the relative lengths of the three spines on the third endopod segment of legs 2 and 3. In the new species the outer spine is nearly twice the length of the two terminal spines, a condition not seen in the three previously described forms. Furthermore, in the new species the caudal ramus is shorter (female 1.5:1, male 1.3:1) than in any of the three previously known species (where the ratio in the female is at least 2.65:1 or longer and in the male 2.0:1 or longer).