Guernea ipilya Thomas & Barnard, 1991

Myers, Alan A., 2009, Dexaminidae *, Zootaxa 2260 (1), pp. 393-424 : 397-400

Guernea ipilya Thomas & Barnard, 1991

( Figs 3 , 4 )

Guernea ipilya Thomas & Barnard, 1991: 301–306 , figs. 1–4 (part).

Material examined. 2 males, 15 females, 1 juvenile, AM P78021 ( JDT / LIZ 17 ) ; 2 females, AM P78022 ( JDT / OPH 4 ) ; 1 female, AM P70638 ( QLD 1621 ) ; 1 female, AM P70978 ( QLD 1684 ) ; 1 female, AM P71050 ( QLD 1706 ) ; 1 female, AM P71027 ( QLD 1714 ) ; 1 female, AM P71093 ( QLD 1716 ) ; 1 female, AM P71172 ( QLD 1723 ) ; 1 female, AM P71150 ( QLD 1732 ) ; 1 male, AM P71135 ( QLD 1742 ) ; 1 female, AM P71167 ( QLD 1751 ) ; 1 juvenile, AM P71178 ( QLD 1751 ) ; 1 female, AM P71301 ( QLD 1761 ) ; 1 female, AM P71385 ( QLD 1791 ) ; 1 female, AM P71398 ( QLD 1801 ) ; 30 males, AM P71415 ( QLD 1805 ) ; 5 males, AM P71521 ( QLD 1805 ) ; 1 male, AM P71469 ( QLD 1821 ) ; 1 male, 1 female, GCRL 2895 ( SEL /LZI-1-3) ; 1 male, 1 female, GCRL 2896 ( SEL /LZI-2-3) ; 1 female, GCRL 2897 ( SEL /LZI-5-1) .

Type Locality. Near Lizard Head , Lizard Island, Queensland, Australia (~ 14°41’S 145°28’E) .

Description. Based on 7 females, 1.9–2.4 mm AM P78021.

Head. Head lateral lobes rounded. Eye medium, smaller than lateral lobe. Antenna 1 peduncle article 1 without short, dense brush setae lining posterior margin. Antenna 2 short, not longer than head; peduncle article 4 without short, dense brush setae lining anterior margin; flagellum short, 3-articulate. Mandible palp absent. Maxilla 1 palp stout, about three times as long as broad, with slender apical process, with 2 apical slender setae. Maxilla 2 inner plate shorter than outer plate, with sparse apical slender setae, inner margin without setae. Maxilliped palp 4-articulate.

Pereon. Gnathopod 2 carpus subequal in length to propodus. Pereopods 3–7 simple or scarcely prehensile. Pereopod 3 carpus with large robust setae on posterior margin. Pereopod 5 coxa posterior lobe enlarged, much deeper than anterior lobe. Pereopods 5–7 of diverse morphology. Pereopod 6 basis, posterior margin straight. Pereopod 7 coxal gill absent; merus and carpus expanded; carpus broadly ovate, not enveloping propodus; propodus subequal to carpus in length.

Pleon. Urosomite 1 without dorsal hump, without dorsal keel, with 2 dorsolateral carinae. Urosomite 2–3 fused, without dorsal humps, with 2 dorsolateral carinae, without dorsal robust setae. Uropods 1–2 inner ramus subequal to outer in length; apical robust setae of rami short, distinctly less than one-half length of corresponding ramus. Uropod 1 peduncle without basofacial slender setae. Uropod 3 peduncle without distolateral robust seta; inner ramus, inner margin without plumose slender setae; outer ramus, inner margin without long plumose slender setae, outer margin without robust seta. Telson lobes with slender apical setae.

Male (sexually dimorphic characters). Based on 6 males, 1.9–2.0 mm, AM P71415; 2 males, 1.8–2.1 mm, AM P78021. Head lateral lobes acute or subacute. Eye very large, covering most of lateral lobe. Antenna 1 peduncle article 1 with short, dense brush setae lining posterior margin. Antenna 2 moderately long, approximately half length of body; peduncle article 4 with short, dense brush setae lining posterior margin; flagellum long, multiarticulate. Uropod 3 peduncle with distolateral robust seta; inner ramus, inner margin with long plumose slender setae; outer ramus, inner margin with long plumose slender setae .

Habitat. On rubble or sand bottoms in back reef, reef flat or patch reef habitats at depths of 0.3– 23 m. Often found among mixed red, brown and green algae growing on rubble or sand. Males often occur in night plankton.

Remarks. Guernea ipilya is very close to the Indonesian species G. sulawesiensis Ortiz & Lalana, 1997 and to the Madagascar species G. latipes Ledoyer, 1979 . It differs from the former in the double carinae of the urosomites ( G. sulawesiensis lacks these) and from the latter in the consolidated eye of the female (ommatidia more dispersed in G. latipes ), the more densely setose peduncle articles of the antennae in the male, the more setose pereopods 5–6 and the shorter apical robust setae on the rami of uropods 1–2. It can be separated from the five other species in the genus currently known from Australia ( G. endota J.L. Barnard, 1972a ; G. gelane J.L. Barnard, 1972a ; G. melape J.L. Barnard, 1972a ; Guernea unchalka J.L. Barnard, 1972a ; G. yamminye Thomas & Barnard, 1991 ) by the 1-articulate palp of maxilla 1 ( G. gelane and G. melape have a 2-articulate palp), the broadly expanded merus and carpus of pereopod 7 (more weakly expanded in G. endota , G. gelane , G. melape and G. unchalka ), the lack of dorsal robust setae on urosomites 2+3 ( G. endota and G. melape have dorsal robust setae) and the lack of short robust setae on the rami of uropod 3 (all five of the other Australian species have at least one robust seta on the rami of uropod 3). It further differs from G. yamminye , with which it co-occurs on Lizard Island, in the shorter carpus of gnathopod 2, the less posterodistally produced carpus and longer propodus of pereopod 7, the lack of dorsal humps on urosomites 1 and 2+3 ( G. yamminye has three very pronounced dorsal humps on the urosomites), the pair of dorsolateral carinae on urosomite 1 ( G. yamminye has one median carina), the short apical robust setae on the rami of uropods 1–2 (long in G. yamminye ) and the lack of a plumose slender seta on the inner ramus of uropod 3 in the female (present in G. yamminye ).

Distribution. Australia. Queensland: Lizard Island, Yonge Reef, Orpheus Island ( Thomas & Barnard 1991, current study).

Figures

FIGURE 3. Guernea ipilya Thomas & Barnard, 1991, holotype, female, 2.0 mm, NMV J20494, near Lizard Head, Lizard Island, Great Barrier Reef (after Thomas & Barnard 1991).

FIGURE 4. Guernea ipilya Thomas & Barnard, 1991, holotype, female, 2.0 mm, NMV J20494, near Lizard Head, Lizard Island (after Thomas & Barnard 1991); male, 1.9 mm, AM P71415, Third Beach, Lizard Island, Great Barrier Reef.