Paracorophium nana, Myers, 2009

Myers, Alan A., 2009, Corophiidae *, Zootaxa 2260 (1), pp. 373-379 : 373-376

Paracorophium nana sp. nov.

( Figs 1 , 2 )

Type material. Holotype, male, 1.8 mm, AM P70806, Ferriers Creek , Lizard Island (14 o 39’56”S 145 o 27’03”E), algae from rocks at edge of mangroves ( Rhizophora stylosa ), hand collected, 0.5 m, S.E. LeCroy, R. A. King, K.N. Klebba & T. Krapp-Schickel, 23 February 2005 (QLD 1655) . Paratype: female, 1.9 mm, same data as holotype, AM P70806 (QLD 1655) .

Other material examined. 1 male, AM P70805 (QLD 1655) ; 2 females, AM P70924 (QLD 1677) ; 1 male, 7 females SEL/LZI 6-2.

Type locality. Ferriers Creek , Lizard Island, Queensland, Australia .

Etymology. Named for its very small size.

Description. Based on holotype, male 1.8 mm, AM P70806.

Head. Head lateral cephalic lobes rounded; eye large, composed of many ommatidia. Antenna 1 very short, less than one third body length; flagellum composed of 4–5 articles; accessory flagellum absent. Antenna 2 short, subequal in length with antenna 1; article 4 lacking a posterodistal lobe; flagellum with 3 articles. Mandible palp articles 2 and 3 subequal; article 3 subovoid with long distal setae.

Pereon. Gnathopod 1 coxa enlarged, distally expanded; carpus longer than propodus, posterior margin densely setose; propodus subchelate. Gnathopod 2 merus enlarged and distally free, with dense long setae forming a sieve together with setae on carpus; propodus slender, twice as long as broad, with posterodistal spine and palmar excavation; dactylus greatly overlapping palm. Pereopods 5–7 basis posterior margin with dense pectinate setae.

Pleon. Urosomites fused. Uropod 1 peduncle with short distoventral spine; rami margins with robust setae and with terminal cluster of robust setae. Uropod 2 inner ramus subequal in length with peduncle; outer ramus much shorter than inner ramus. Uropod 3 biramous; peduncle without distal expansion; outer ramus minute.

Female (sexually dimorphic characters). Based on paratype, female, 1.9 mm, AM P70806. Gnathopod 2 propodus slender, lacking posterodistal spine .

Habitat. Algae near mangroves.

Remarks. This species is similar to P. brisbanensis Chapman, 2002 , but differs in a number of ways. The male antenna 2 article 4 lacks a posterodistal lobe; the mandible palp is much shorter with article 3 sub-ovoid; the carpus of gnathopod 1 is much more slender; the propodus of gnathopod 2 is also slender with a short posterodistal spine and weakly developed palmar spine; uropods 1–2 have fewer, weaker robust setae; the uropod 1 distoventral spine is acute (rounded in P. brisbanensis ); uropod 3 inner ramus has a marginal robust seta (absent in P. brisbanensis ). In addition, this species is much smaller, at less the 2.0 mm ( P. brisbanensis up to 4.4 mm).

Distribution. Australia. Queensland: Lizard Island (current study).

Figures

FIGURE 1. Paracorophium nana sp. nov., holotype, male 1.8 mm, AM P70806, Ferriers Creek, Lizard Island, Great barrier Reef.

FIGURE 2. Paracorophium nana sp. nov., holotype, male 1.8 mm, paratype, female 1.9 mm, AM P70806, Ferriers Creek, Lizard Island, Great barrier Reef.