Colomastix japonica Bulycheva, 1955

LECROY, SARA E., 2009, Colomastigidae *, Zootaxa 2260 (1), pp. 348-372 : 352-356

Colomastix japonica Bulycheva, 1955

( Figs 3 , 4 )

Colomastix japonica Bulycheva, 1955: 197–200 , fig. 3. — Ariyama, 2005: 8–15, figs 5–9.

Colomastix lunalilo . — Hirayama, 1990: 21–24, figs 1–3 (not Colomastix lunalilo J.L. Barnard, 1970: 96–100 , figs 51, 52).

? Colomastix lunalilo . — Kim & Kim, 1987: 9, fig. 8 (not Colomastix lunalilo J.L. Barnard, 1970: 96–100 , figs 51, 52).

Material examined. 5 males, 6 females, 3 juveniles, AM P37542 ( QLD 1 ) ; 1 male, AM P78987 ( JDT / LIZ 7 ) .

Type locality. Peter the Great Bay, Russia .

Description. Based on 5 males, 3 juveniles, AM P37542.

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 strongly concave, weakly serrate, with 1 ventral tooth. Antennae 1–2 marginal robust setae moderately long. Antenna 1 peduncle article 1, dorsomedial margin with 5–6 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 2–3 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 subequal 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 crenulate, with anterodistal notch, without anterodistal process; ischium with inner anterodistal lobe 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, subtriangular, apical margin entire, middle process very small, rounded, process at dactylar hinge broad, subtruncate; 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 with 3 robust setae.

Pleon. Pleopods 1–3 inner ramus with 4 articles, outer ramus with 5 articles. Pleopod 2 peduncle, anteromedial surface with 7 slender setae. Uropod 1 inner ramus modified, not strongly falcate, not expanded proximally, ventral margin straight, tip minutely attenuate or subacute, straight, with 2–5 subapical robust setae dorsally; outer ramus slightly shorter than inner ramus, tip lanceolate, subacute. Uropod 2 both rami, ventral margin lacking setae. Uropod 3 peduncle approximately 3.5 x as long as deep; inner ramus blade-like, approximately twice length of outer ramus, medial surface with proximal, slightly curved diagonal ridge, ridge lined with minute robust setae. Telson narrowly subtriangular, dorsal surface flat, tip subtriangular, without lobes or processes, with 2 apical short slender setae.

Female (sexually dimorphic characters). Based on 6 females, AM P37542. Head deeper than long, subequal in length to pereon segment 1. Antennae 1–2 marginal robust setae elongate. Oostegite 2 subovate (length:width ratio approximately 2:1), approximately twice as long as basis of gnathopod 2. Gnathopod 2 basis linear, unexpanded distally, anterior margin entire, without anterodistal notch; ischium with inner anterodistal lobe not expanded; propodus unenlarged, palm without teeth or processes; dactylus, insertion on propodus subapical, without process on posterior margin. Uropod 1 inner ramus unmodified, lanceolate; outer ramus subequal to inner ramus.

Adult body length. 4.0– 10.3 mm. Males attain slightly larger sizes than females.

Colour in life. Unknown.

Host. The sponges Callyspongia confoederata ( Ridley, 1884) ; Callyspongia elegans ( Thiele, 1899) ; Haliclona permollis ( Bowerbank, 1866) ; Myxilla setoensis Tanita, 1961 ; Siphonocholina sp. ( Kim & Kim 1987, Hirayama 1990, Ariyama 2005).

Habitat. Coral rubble and patch reefs.

Depth range. 1–18 m.

Remarks. Colomastix japonica was originally described by Bulycheva (1955) from Peter the Great Bay in Russia and was recently redescribed by Ariyama (2005) based on material from several locations in Japan. Ariyama (2005) compares C. japonica with C. lunalilo and notes that material reported as the latter species from Cheju Island, Korea ( Kim & Kim 1987) and Noumea, New Caledonia ( Hirayama 1990) actually represents C. japonica based on body size ( C. lunalilo is a much smaller species) and morphology. The Korean material is somewhat problematic because it is fairly sketchily described and illustrated, but it does appear closer to C. japonica than C. lunalilo based on body size and the relative lengths of the rami of uropod 3. However, based on the information provided in Kim & Kim (1987), C. dentipalma sp. nov. and C. brazieri cannot be completely ruled out as possibilities because they are similar in size and have similar pereopod and uropod 3 morphologies to C. japonica . The Korean material appears to differ from both C. japonica and C. dentipalma sp. nov. in the relatively unexpanded basis of gnathopod 2 in the male, resembling C. brazieri in this regard. The New Caledonian material is fully illustrated ( Hirayama 1990) and is clearly C. japonica . Material from Lizard Island agrees well with the descriptions and illustrations in Bulycheva (1955), Hirayama (1990) and Ariyama (2005) and extends the known range of this species to the Great Barrier Reef.

Colomastix japonica can be distinguished from all other known species in the genus by the combination of a crenulate anterior margin and an anterodistal notch on the basis of gnathopod 2 of the male, an elongate peduncle and a blade-like inner ramus on uropod 3 that is approximately twice the length of the outer ramus, a narrowly subtriangular telson and the modification of the tip of the inner ramus of uropod 1 in the male.

Distribution. Australia: Lizard Island, Queensland (current study). New Caledonia: Noumea ( Hirayama 1990, as C. lunalilo ). Korea:?Cheju Island ( Kim & Kim 1987, as C. lunalilo ). Japan: Shirahama and Oura, Wakayama; Tanigawa, Osaka; and Iwagi Island, Ehime ( Ariyama 2005). Russia: Peter the Great Bay ( Bulycheva 1955).

Figures

FIGURE 3. Colomastix japonica Bulycheva, 1955, male, 4.5 mm, female, 4.0 mm, AM P37542, Watsons Bay, Lizard Island, Great Barrier Reef.

FIGURE 4. Colomastix japonica Bulycheva, 1955, male, 4.5 mm, female, 4.0 mm, AM P37542, Watsons Bay, Lizard Island, Great Barrier Reef.