Mycoxynus fungianus Humes 1978

Mycoxynus fungianus

TYPE MATERIAL.—20 , 28 , and 8 copepodids from one Fungia (Ctenactis) echinata (Pallas), in 3 m, southwestern shore of Goenoeng Api, Banda Islands, 4°31′45″S, 129°51′55″E, 25 May 1975. Holotype , allotype, and 40 paratypes (16 , 24 ) deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C.; the remaining paratypes (dissected) in the collection of the author.

FEMALE.—Body (Figure 18a) elongated and slender, similar to that of Mycoxynus longicauda Humes, 1973. Length 1.58 mm (1.50–1.75 mm) and greatest width 0.47 mm (0.44–0.51 mm), based on 10 specimens. Ratio of length to width of prosome 2.03: 1. Ratio of length of prosome to that of urosome 1.46: 1.

Segment of leg 5 (Figure 18b) 176 × 275. Genital segment 169 × 220, wider than long. Genital areas situated dorsally in anterior half of segment. Each area (Figure 18c) with two small naked setae about 10 long. Three postgenital segments from anterior to posterior 91 × 125, 78 × 107, and 104 × 84. Posteroventral margin of anal segment smooth.

Caudal ramus (Figure 18d) greatly elongated, 166 × 14, width taken at middle. Ratio of length to width 11.9: 1. Outer lateral seta 23. Dorsal seta 25. Outermost terminal seta 21, innermost terminal seta 23, and two median terminal setae 94 (outer) and 121 (inner). All setae naked.

Body surface with numerous small refractile areas and a few small hairs (sensilla).

Egg sac (Figure 18c) moderately elongated, length 638–693, width 253. Two sacs in most preserved specimens adhering together (in only one female separate). Each egg about 112 in diameter.

Rostrum (Figure 18f–h) linguiform in ventral view and projecting in lateral view. First antenna (Figure 18i) 285 long and 7-segmented, though separation of segments 2 and 3 distinct only on dorsal surface. Lengths of segments: 50 (99 along anterior margin), 88, 16, 29, 26, 16, and 11 respectively. Armature: 4, 13, 6, 3, 4 + 1 aesthete, 2 + 1 aesthete, and 7 + 1 aesthete. All setae naked.

Second antenna (Figure 18j) 263 long and 3-segmented. First and second segments with single small inner seta. Third segment lacking setae, 116 along outer edge, 71 along inner edge, and 26 wide. Terminal claw 40, sharply pointed and sinuous (Figure 18k).

Labrum (Figure 18l) with two moderately slender posteroventral lobes. Mandible (Figure 18m), paragnath (Figure 18l), first maxilla (Figure 18n), and second maxilla (Figure 19a) resembling those of Mycoxynus longicauda except for small details. Maxilliped (Figure 19b) 3-segmented and arched anteriorly. Second segment broad in flat outer view (Figure 19c) with two small unequal naked setae and distal transverse outer row of spinules. Third segment bluntly pointed distally and bearing a naked seta. Ventral area between maxillipeds and first pair of legs similar to that of M. longicauda.

Leg 1 (Figure 19d) with 3-segmented rami. Leg 2 (Figure 19g) with 3-segmented exopod and 2-segmented endopod. Leg 3 (Figure 19h) and leg 4 (Figure 19i) with 2-segmented exopods but lacking endopods. Spine and setal formula for legs 1–4 as follows (Roman numerals representing spines, Arabic numerals setae):

Exopod spine with mucronate tip (Figure 19e). In one female right endopod of leg 1, 2-segmented (Figure 19f). Endopod of leg 2 showing very slight indication of division of second segment.

Leg 5 (Figure 19j) with small free segment 15.5 × 18.5. Two terminal setae 33 and 22. Dorsal setae 45. All setae naked.

Leg 6 represented by two setae on genital area (Figure 18c).

Living specimens in transmitted light gray, intestine pale orange tan, eye red, egg sacs opaque gray.

MALE.—Body (Figure 20a) slender as in female. Length 1.32 mm (1.28–1.36 mm) and the greatest width 0.38 mm (0.35–0.40 mm), based on 10 specimens. Ratio of length to width of prosome 1.85: 1. Ratio of length of prosome to that of urosome 1.12: 1.

Segment of leg 5, 78 × 265. Genital segment (Figure 20b) 133 × 250, wider than long. Four postgenital segments from anterior to posterior, 81 × 130, 73 × 101, 62 × 86, and 91 × 70.

Caudal ramus resembling that of female, 152 × 13, ratio 11.8: 1.

Rostrum like that of female. First antenna similar to that of female, but three aesthetes added as in male of M. longicauda, so that formula is: 4, 13 + 2 aesthetes, 6, 3 + 1 aesthete, 4 + 1 aesthete, and 7 + 1 aesthete.

Second antenna, labrum, mandible, paragnath, first maxilla, and second maxilla like those in female. Maxilliped (Figure 20c) resembling that of M. longicauda, but claw a little stouter and 73 along axis.

Ventral area between maxillipeds and first pair of legs as in female.

Legs 1–4 similar to those of female, but second segment of endopod of leg 2 showing a little stronger evidence of subdivision and in one specimen 3-segmented (Figure 20d).

Leg 5 (Figure 20e) with free segment 11 × 9.

Leg 6 (Figure 20f) the usual posteroventral flap on genital segment, bearing two naked setae 47 and 34.

Spermatophore (Figure 20g) attached to female in pairs, sausage shaped, about 400 × 120, not including neck. Surface transversely striated.

Living specimens with color resembling that of female.

ETYMOLOGY.—The specific name fungianus is a combination of Fungia and the Latin suffix -anus (belonging to).

COMPARISON WITH Mycoxynus longicauda.—The following features of Mycoxynus fungianus distinguish it from M. longicauda, an associate of Parahalomitra irregularis (Gardiner) in New Caledonia: (1) the shorter body length, 1.58 mm, 1.32 mm versus 1.80 mm and 1.57 mm; (2) the shorter caudal ramus, 166, 152 versus 268 and 208; (3) legs 1 and 2 with four spines on the third segment of the exopod versus three such spines; (4) legs 3 and 4 with the ramus 2-segmented versus 3-segmented; and (5) the claw of the female second antenna 40 versus 20.

Odontomolgus Humes and Stock, 1972