Colomastix dentipalma, LeCroy, 2009

LECROY, SARA E., 2009, Colomastigidae *, Zootaxa 2260 (1), pp. 348-372 : 349-352

Colomastix dentipalma sp. nov.

( Figs 1 , 2 , Pl. 2E)

Type material. Holotype, male, 4.9 mm, AM P78981, Blue Lagoon Bommie , Lizard Island (14°41.24'S 145°27.93'E), unidentified sponge, 8 m, K. Klebba, 4 March 2005 ( QLD 1804 ) . Paratypes: 1 male, AM P78982, North Point , Lizard Island, rubble at base of rock cliff, 12 m, J. D. Thomas, 28 January, 1989 ( JDT / LIZ 13 ) ; 1 male, 1 female, AM P71339 ( QLD 1804 ), same data as holotype ; 4 males, 7 females, AM P71429 ( QLD 1804 ), same data as holotype .

Additional material examined. 1 male, 1 female, AM P27022 ( QLD 2017 ) .

Type locality. Blue Lagoon Bommie , Lizard Island, Queensland, Australia (14°41.24'S 145°27.93'E) .

Etymology. From the Latin ' dentis ', meaning 'tooth', and ' palma ', meaning 'hand', referring to the acute processes at the palmar angle of the propodus on gnathopod 2 of the female.

Description. Based on holotype male, 4.9 mm, AM P78981 and 4 paratype males, AM P71429.

Head. Head as long as deep, subequal in length to pereon segment 1 and half of pereon segment 2 combined; rostrum subacute; interantennal plate with anteroventral angle extending far beyond anterodorsal angle, anterior margin straight to slightly concave, weakly serrate, with 2 ventral teeth. Antennae 1–2, marginal robust setae elongate. Antenna 1 peduncle article 1, dorsomedial margin with 3–5 robust setae. Antenna 2 peduncle articles 3–5, ventrolateral margin without small, triangular robust setae; peduncle article 3, distomedial angle with 1 robust seta, without slender setae or process, dorsomedial margin with 2 robust setae, ventromedial surface with 2 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 flattened.

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 smaller than gill 5. Gnathopod 1 elongate, slender; propodus with pectinate apical setae. Gnathopod 2 basis broadly expanded distally, anterior margin entire, with anterodistal notch, without anterodistal process; ischium with inner anterodistal lobe not expanded; carpus much shorter than propodus, inner ventral surface without patch of setae; propodus greatly enlarged, inner ventral surface with patch of setae, setae elongate, slender, palm not excavate, with 3 dissimilar, unequally spaced processes, palmar angle with 2 processes, proximal process distinctly larger than middle process, subtruncate, apical margin minutely serrate, middle process small, subacute, process at dactylar hinge broad, subtriangular; dactylus, insertion on propodus apical, with small process on posterior margin, tip lanceolate, subacute. Pereopods 3–4 basis produced anterodistally to form rounded lobe. Pereopods 3–7 basis slightly expanded. Pereopod 7 propodus, anterior margin with 3–4 robust setae.

Pleon. Pleopods 1–3 inner ramus with 4 articles, outer ramus with 5 articles. Pleopod 2, peduncle, anteromedial surface with 5 slender setae. Uropod 1 inner ramus modified, not strongly falcate, not expanded proximally, ventral margin straight, tip minutely bifurcate, dorsal branch of bifurcation longer than ventral branch, both branches straight; outer ramus slightly shorter than 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 blade-like, approximately twice length of outer ramus, medial surface with proximal, curved diagonal ridge, ridge lined with minute robust setae. Telson narrowly subtriangular, dorsal surface flat, tip subtriangular, without lobes or processes, with 2 apical elongate slender setae.

Female (sexually dimorphic characters). Based on 7 paratype females, AM P71429. Oostegite 2 subovate (length:width ratio approximately 2:1), approximately twice as long as basis of gnathopod 2. Gnathopod 2, basis linear, unexpanded distally, without anterodistal notch; propodus slightly enlarged, palm with 2 processes, processes subequal in size, margins serrate distally; dactylus without process on posterior margin. Pereopods 3–4 basis not produced anterodistally. Pleopod 2 peduncle, anteromedial surface without slender setae. Uropod 1, inner ramus unmodified, lanceolate.

Adult body length. 3.4–5.2 mm. Males attain slightly larger sizes than females.

Colour in life. Eyes red. Antennae 1–2 banded with rose pink and pale grey or white; body and pereopods with a faint rose pink wash over translucent grey. Eggs lime green.

Host. Unknown.

Habitat. Sponges, coral rubble.

Depth range. 8–13 m.

Remarks. Colomastix dentipalma sp. nov. belongs to the group of species with an elongate, blade-like inner ramus on uropod 3 in both sexes. This group also includes C. brazieri from south-eastern Australia; C. magnirama Hurley, 1954 from New Zealand; C. lunalilo J.L. Barnard, 1970 from Hawaii; C. japonica Bulycheva, 1955 from the Sea of Japan ( Russia); and C. laminosa Lyons & Myers, 1990 from the Red Sea. It differs from all of the above species by having a moderately enlarged propodus with palmar ornamentation on gnathopod 2 of the female and very elongate apical slender setae on the telson in both sexes. It also differs from all except C. japonica by the presence of a large anterodistal notch in the basis of gnathopod 2 in the male. Colomastix dentipalma sp. nov. can be further distinguished from C. japonica , which it closely resembles, by the presence of a second ventral tooth and a less concave anterior margin on the interantennal plate and by the distally expanded basis and minutely serrate palmar process on gnathopod 2 of the male. In addition, the modification of the tip of the inner ramus of the male uropod 1 differs between the two species.

Distribution. Australia: Queensland: Lizard and Heron Islands (current study).

Figures

FIGURE 1. Colomastix dentipalma sp. nov., paratype, male, 5.2 mm, paratype, female, 3.7 mm, AM P71429, Blue Lagoon Bommie, Lizard Island, Great Barrier Reef.

FIGURE 2. Colomastix dentipalma sp. nov., paratype, male, 5.2 mm, paratype, female, 3.7 mm, AM P71429, Blue Lagoon Bommie, Lizard Island, Great Barrier Reef.