Colomastix processa, LeCroy, 2009

LECROY, SARA E., 2009, Colomastigidae *, Zootaxa 2260 (1), pp. 348-372 : 363-367

Colomastix processa sp. nov.

( Figs 9 , 10 , Pl. 2F)

Type material. Holotype, male, 4.1 mm, AM P71208 ( QLD 1755 ), Horseshoe Reef , Lizard Island (14°41.21'S 145°26.49'E), large coral bommies surrounded by sand and rubble, ex. sponge Spirastrella vagabunda Ridley, 1884 , 8– 12 m, K. Klebba & L. Hughes, 2 March 2005 . Paratypes: 1 female, AM P71215 ( QLD 1760 ), Horseshoe Reef , Lizard Island (14°41.21'S 145°26.49'E), large coral bommies surrounded by sand and rubble, unidentified sponge, 9–10 m, C. Serejo, 2 March 2005 . 4 males, 4 females, AM P71235, same data .

Additional material examined. 1 female, AM P24201 ( SBS 1013005 ) ; 4 males, 2 females, AM P24203 ( SBS 76320) ; 2 males, AM P24205 ( SBS 1013005 ) ; 1 female, AM P24200 ( SBS 0913006 ) ; 1 male, AM P24207 ( SBS 0913006 ) ; 1 male, AM P78983 ( SBS 0913006 ) ; 1 male, 6 females, AM P37536 ( NSW 169 ) .

Type locality. Horseshoe Reef , Lizard Island, Queensland, Australia (14°41.21'S 145°26.49'E) .

Etymology. From the Latin ' processus ', meaning 'go forward, advance', referring to the anteriorly directed spur on the anteroventral margin of the basis of gnathopod 2 in the male.

Description. Based on holotype, male, 4.1 mm, AM P71208 and paratype series of 4 males, AM P71235.

Head. Head as long as deep, subequal in length to pereon segment 1 and half of pereon segment 2 combined; rostrum absent; interantennal plate with anteroventral angle extending slightly beyond anterodorsal angle, anterior margin straight to slightly concave, weakly serrate, with 1 ventral tooth. Antennae 1–2 marginal robust setae moderately long. Antenna 1 peduncle article 1, dorsomedial margin with 4–5 robust setae. Antenna 2 peduncle articles 3–5, ventrolateral margin without small, triangular robust setae; peduncle article 3, distomedial angle with 2 robust setae, without slender setae or process, dorsomedial margin with 1– 2 robust setae, ventromedial surface without robust setae; peduncle article 5, dorsal margin without stubby robust setae. Mouthparts other than maxilliped moderately reduced. Maxilliped inner plates completely fused, basal shell expanded to form a ventral keel, keel distally rounded.

Pereon. Coxa 1 anterior margin strongly concave, anteroventral angle narrowly produced. Coxae 1–4 with small anteroventral cusp. Coxal gills 2–5 gradually increasing in size, gill 6 subequal to gill 5. Gnathopod 1 elongate, slender; propodus with pectinate apical setae. Gnathopod 2 basis moderately expanded distally, anterior margin entire, without anterodistal notch, with anterodistal process; ischium with inner anterodistal lobe expanded; carpus slightly shorter than propodus, inner ventral surface with patch of setae, setae short, very fine; propodus slightly enlarged, inner ventral surface with patch of setae, setae short, very fine or setae elongate, slender, palm not excavate, with 4 dissimilar, unequally spaced processes, palmar angle with 2 processes, proximal process subequal to adjacent middle process, subtriangular, apical margin entire, both middle processes broad, rounded, process at dactylar hinge small, 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 without slender setae. Uropod 1 inner ramus modified, not strongly falcate, not expanded proximally, ventral margin straight, tip bulbous, with small subapical slender seta, with acute triangular dorsoapical process (may occasionally be absent or broken); outer ramus three-fourths length of inner ramus, tip lanceolate, subacute. Uropod 2 both rami, ventral margin lacking setae. Uropod 3 peduncle twice as long as deep; inner ramus lanceolate, slightly longer than outer ramus, ventral margin lacking setae. Telson broadly subtriangular, dorsal surface convex, tip rounded, with 3 lobes or processes, with 1–2 apical minute slender setae.

Female (sexually dimorphic characters). Based on paratype series of 4 females, AM P71235. Oostegite 2 narrowly subovate (length:width ratio 3:1 or greater), approximately twice as long as basis of gnathopod 2. Gnathopod 2 basis linear, unexpanded distally, with anterodistal notch, without anterodistal process; ischium with inner anterodistal lobe not expanded; carpus subequal to propodus in length; propodus unenlarged, inner ventral surface with patch of setae, setae short, very fine, palm without teeth or processes; dactylus, insertion on propodus subapical, without process on posterior margin. Pereopods 3–7 basis unexpanded. Uropod 1 inner ramus unmodified, lanceolate; outer ramus slightly shorter than inner ramus. Uropod 3 inner ramus approximately one-third longer than outer ramus. Telson tip without lobes or processes.

Adult body length. 3.2–6.4 mm. Males attain slightly larger sizes than females.

Colour in life. Eyes with small, discrete, red spots on a white background. Antennae banded with reddish pink in the male, banding pale or absent in the female; pereon and pleon with large reddish blocks of pigment on a translucent grey or whitish background, coxae each with a single large pigment spot anterodistally. This pattern is similar to that of Colomastix plumosa , but the lateral pigment blocks on the pereon segments are single in C. plumosa rather than double as in C. processa sp. nov. and the placement of the coxal spots is proximal vs. anterodistal. Also, the antennae are more strongly banded in the female and there is lateral pigmentation on pleon segment 3 in C. plumosa .

Host. The sponges Spirastrella vagabunda Ridley, 1884 ; Polymastia craticia Hallmann, 1912 ; and Teichonopsis labyrinthica ( Carter, 1886) .

Habitat. Coral reef, rock and rubble habitats.

Depth range. 8–25 m.

Remarks. Colomastix processa sp. nov. differs from all other known species of Colomastix in the ornamentation of the anterior margin of the basis of gnathopod 2 in both sexes, with an anterodistal process in the male and an anterodistal notch in the female. It does not appear to be closely similar to any known species of Colomastix , although the bulbous modification of the tip of the inner ramus of uropod 1 in the male resembles that of three Atlantic species of the genus, C. bousfieldi , C. heardi and C. gibbosa LeCroy, 1995 . However, unlike these three species, there is no subapical dorsal notch on the inner ramus of uropod 1 in C. processa sp. nov. and the tip is more highly modified. The broadly rounded frontal margin of the head in this species is similar to that of C. brevicornis Ledoyer 1982 , but the antennae, gnathopods, uropods and telson are all quite different from those of that species. Gnathopod 2 of the male is quite distinctive as well, with an enlarged carpus and only moderately enlarged propodus. Although C. laminosa and C. azumai Hirayama & Kikuchi 1980 appear to share this feature based on their original descriptions ( Lyons & Myers 1990; Hirayama & Kikuchi 1980), the material on which these descriptions were based appears to be immature and the relative proportions of these articles changes developmentally. The adult male remains unknown for C. laminosa , but the adult male of C. azumai has a greatly enlarged propodus and a small carpus ( Ariyama 2005). Colomastix processa is currently only known from its type locality on Lizard Island and from several locations in New South Wales.

Distribution. Australia. New South Wales: Port Jackson, Turrametta Head, Mona Vale and Broken Bay (current study). Queensland: Lizard Island (current study).

Figures

FIGURE 9. Colomastix processa sp. nov., paratype, female, 3.2 mm, paratype, male, 4.2 mm, AM P71235, Horseshoe Reef, Lizard Island, Great Barrier Reef.

FIGURE 10. Colomastix processa sp. nov., paratype, female, 3.2 mm, paratype, male, 4.2 mm, AM P71235, Horseshoe Reef, Lizard Island, Great Barrier Reef.