Colomastix plumosa Ledoyer, 1979

LECROY, SARA E., 2009, Colomastigidae *, Zootaxa 2260 (1), pp. 348-372 : 360-363

Colomastix plumosa Ledoyer, 1979

( Figs 7 , 8 )

Colomastix plumosa Ledoyer, 1979: 26 , fig. 8(1). — Ledoyer, 1982: 158–159, fig. 55. — Lyons & Myers, 1990: 1220– 1221, fig. 18. — Ariyama, 2005: 27–31, figs 19–22.

? Colomastix pusilla . — Nayar, 1966: 145, fig. 7 (not Colomastix pusilla Grube, 1861: 137 ).

Material examined. 1 male, AM P79275 ( JDT / LIZ 3 ) ; 1 male, AM P79276 ( JDT / LIZ 5 ) ; 1 male, GCRL 2873 ( JDT / LIZ 5 ) ; 1 male, AM P79277 ( JDT / LIZ 7 ) ; 1 male, AM P79278 ( JDT / LIZ 12 ) ; 3 males, 1 female, AM P79279 ( JDT / LIZ 13 ) ; 1 female, GCRL 2874 ( JDT / LIZ 13 ) ; 1 male, AM P79280 ( JDT / LIZ 14 ) ; 2 males, 1 female, AM P79281 ( JDT / OPH 1 ) ; 1 juvenile, AM P79282 ( QLD 11 ) ; 1 juvenile, AM P37541 ( QLD 27 ) ; 1 female, AM P70593 ( QLD 1622 ) ; 1 female, AM P70709 ( QLD 1643 ) ; 1 juvenile, AM P70735 ( QLD 1643 ) ; 1 female, AM P79283 ( QLD 1760 ) ; 1 female, AM P79284 ( QLD 1760 ) ; 1 juvenile, AM P71325 ( QLD 1786 ) ; 1 male, AM P71434 ( QLD 1792 ) .

Type locality. Grand Récif de Tuléar , Madagascar (23°20’S 43°41’E) .

Description. Based on 1 male, AM P79278 (JDT/LIZ 12); 2 males, AM P79281 (JDT/OPH 1).

Head. Head longer than deep, slightly longer than first two pereon segments combined; rostrum narrowly rounded; interantennal plate with anterodorsal and anteroventral angles extending forward subequally, anterior margin straight to slightly concave, without serrations, without ventral teeth. Antennae 1–2 marginal robust setae short. Antenna 1 peduncle article 1, dorsomedial margin with 2 robust setae. Antenna 2 peduncle articles 3–5, ventrolateral margin with small, triangular robust setae; peduncle article 3, distomedial angle with 1 robust seta and 1 elongate slender seta, without process, dorsomedial margin and ventromedial surface without robust setae; peduncle article 5, dorsal margin with stubby robust setae. Mouthparts other than maxilliped greatly reduced or vestigial. Maxilliped, inner plates completely fused, basal shell not expanded to form a ventral keel.

Pereon. Coxa 1 anterior margin convex, anteroventral angle rounded. Coxae 1–4 without small anteroventral cusp. Coxal gills 2–5 gradually increasing in size, gill 6 smaller than gill 5. Gnathopod 1 vestigial, exact morphology individually variable; propodus without setae. Gnathopod 2 basis broadly expanded distally, anterior margin entire, without anterodistal notch, without anterodistal process; ischium with inner anterodistal lobe not expanded; carpus much shorter than propodus, inner ventral surface with patch of setae, setae short, very fine; propodus greatly enlarged, inner ventral surface with patch of setae, setae elongate, slender, palm not excavate, with 3 similar, equally spaced processes, palmar angle with 1 short subtriangular process, apical margin of process entire, middle process slightly smaller than proximal process, subacute, process at dactylar hinge medium, subtriangular; dactylus, insertion on propodus apical, with small process on posterior margin, tip lanceolate, subacute. Pereopods 3–4 basis not produced anterodistally. Pereopods 3–7 basis slightly expanded. Pereopod 7 propodus, anterior margin without setae.

Pleon. Pleopods 1–3 inner ramus with 4 articles, outer ramus with 4 articles. Pleopod 2 peduncle, anteromedial surface with 3 slender setae. Uropod 1 inner ramus modified, not strongly falcate, expanded proximally, ventral margin straight, tip subtruncate; outer ramus three-fourths length of inner ramus, tip lanceolate, subacute. Uropod 2 both rami, ventral margin lacking setae. Uropod 3 peduncle less than twice as long as deep; inner ramus lanceolate, subequal to outer ramus, ventral margin lacking setae. Telson broadly subtriangular, dorsal surface flat, tip subtruncate, without lobes or processes, with 2 subapical short slender setae.

Female (sexually dimorphic characters). Based on 1 female, GCRL 2874 and 1 female, AM P79281 (JDT/OPH 1). Head as long as deep, subequal in length to pereon segment 1 and half of pereon segment 2 combined. Antenna 2 peduncle article 5, dorsal margin without stubby robust setae. Mouthparts other than maxilliped moderately reduced. Oostegite 2 narrowly subovate (length:width ratio 3:1 or greater), slightly longer than basis of gnathopod 2. Gnathopod 1 elongate, slender; propodus with simple apical setae. Gnathopod 2 basis weakly expanded distally; carpus subequal to propodus in length, inner ventral surface with patch of setae, setae elongate, very fine; propodus unenlarged, inner ventral surface with patch of setae, setae elongate, very fine, palm without teeth or processes; dactylus without process on posterior margin, tip pleated, subtruncate. Pleopod 2 peduncle, anteromedial surface without slender setae. Uropod 1 inner ramus unmodified, lanceolate; outer ramus subequal to inner ramus. Uropod 2 both rami, ventral margin densely setose. Uropod 3 inner ramus, ventral margin densely setose.

Adult body length. 2.3–3.0 mm. There appears to be little difference in size between males and females in this species.

Colour in life. Eyes red. Antennae banded with reddish pink, pereon and pleon with large reddish pink blocks of pigment on translucent grey background, coxae each with a single large pigment spot proximally. This pattern is similar to that of Colomastix processa sp. nov. (see Colour in life section of C. processa sp. nov. for a comparison of the two species).

Host. The sponges Spirastrella insignis Thiele, 1898 and Clathria fasciculata Wilson, 1925 ( Ariyama 2005) .

Habitat. Corals, coral rubble, algae ( Caulerpa racemosa J. Agardh, 1873 ; Halimeda micronesica Yamada, 1941 ) and algal turf in reef slope, reef flat and patch reef habitats.

Depth range. 1–28 m.

Remarks. Colomastix plumosa is a fairly widespread species in the Indian Ocean and Red Sea, although it has not previously been reported from the Indo-Pacific or Pacific Oceans south of Japan. Nayar's (1966) report of C. pusilla Grube, 1861 from India may actually refer to this species. He does not illustrate uropod 2 of his specimen, which appears to be either a female or a small subadult male and has a setose inner ramus on uropod 3, as do C. plumosa , C. semiplumosa Ariyama, 2005 and C. minispinosa Ren, 2006 (possibly a synonym of C. semiplumosa ). However, uropod 1 of Nayar's material has subequal rami, resembling that of C. plumosa rather than C. semiplumosa or C. minispinosa , both of which have distinctly unequal rami on uropod 1 in the female. The adult male of C. plumosa was unknown prior to the current study.

Although there are several other species of Colomastix that have a setose inner ramus on uropod 3 in the female, including the Atlantic species C. bousfieldi LeCroy, 1995 , C. heardi LeCroy, 1995 and C. falcirama LeCroy, 1995 , as well as C. semiplumosa from Japan and C. minispinosa from China, C. plumosa can be distinguished from these and all other known species of Colomastix by the setose inner and outer rami of uropod 2 in the female and by the simple, subtruncate tip of the inner ramus of uropod 1 in the male. It appears to be most similar to C. semiplumosa , which it further resembles in having a pleated tip on the dactylus of gnathopod 2 in the female. This structure appears to be unique to these two species, as well as C. azumai Hirayama & Kikuchi, 1980 and C. littoralis Ariyama, 2005 , also from Japan, and C. thomasi sp. nov. from Lizard Island.

Distribution. Australia. Queensland: Lizard and Orpheus Islands (current study). Japan. Oura and Hikigawa, Wakayama ( Ariyama 2005).? India. Gulf of Mannar: Tuticorin ( Nayar 1966). Madagascar. Grand Récif de Tuléar ( Ledoyer 1979, 1982). Red Sea. Gulf of Aqaba ( Lyons & Myers 1990).

Figures

FIGURE 7. Colomastix plumosa Ledoyer, 1979, male, 2.7 mm, AM P79278, north shore of Palfrey Island, Lizard Island; female, 2.3 mm, AM P79281, cove south of Orpheus Island Resort, Orpheus Island, Great Barrier Reef.

FIGURE 8. Colomastix plumosa Ledoyer, 1979, male, 2.7 mm, AM P79278, north shore of Palfrey Island, Lizard Island; female, 2.3 mm, AM P79281, cove south of Orpheus Island Resort, Orpheus Island, Great Barrier Reef.