Elasmopus alalo Myers, 1986

Lowry, J. K. & Hughes, L. E., 2009, Maeridae, the Elasmopus group *, Zootaxa 2260 (1), pp. 643-702 : 646-649

Elasmopus alalo Myers, 1986

( Figs 1 , 2 )

Elasmopus pseudaffinis . —J.L. Barnard, 1965: 501, figs 12, 13. — Ledoyer, 1972: 219, pls 38, 39. — Ledoyer, 1978: 273, fig. 20a (in part). — Berents, 1983: 118, figs 15, 16. — Ledoyer, 1984: 65, fig. 30b. —? Ren, 1998, 203: fig. 6.

Elasmopus alalo Myers, 1986b: 273 , figs 4, 5. — Springthorpe & Lowry, 1994: 8 (catalogue). — Myers, 1995: 27. — Lowry & Stoddart, 2003: 177 (catalogue).

Material examined. 1 female, 7.1 mm, AM P30114 ( QLD 50 ) ; 1 male, 11.5 mm, AM P30115 ( QLD 62 ); 1 unsexed, AM P75706 ( QLD 1846 ); 2 unsexed, AM P75709 ( QLD 1849 ); 1 unsexed, AM P75850 ( QLD 1850 ); 2 unsexed, AM P75710 ( QLD 1851 ); 1 unsexed, AM P75711 ( QLD 1854 ); 2 unsexed, AM P75708 ( QLD 1866 ); many unsexed, AM P75707 ( QLD 2001 ); 2 unsexed, AM P78268 (NT 6) ; 11 unsexed, AM P78258 (NT 16) ; 3 unsexed, AM P78259 (NT 17) ; 4 unsexed, AM P78260 (NT 19) ; 7 unsexed, AM P78261 (NT 22) ; 1 unsexed, AM P78263 (NT 36) ; 5 unsexed, AM P78265 (NT 55) ; 10+ unsexed, AM P78266 (NT 58) ; 10+ unsexed, AM P78267 (NT 59) ; 18 unsexed, AM P78269 (NT 60) ; 7 unsexed, AM P78270 (NT 78) ; 10+ unsexed, AM P78271 (NT 79) ; 1 unsexed, AM P78274 (NT 80) ; 1 unsexed, AM P78262 (NT 345) ; 1 male dissected, 4 slides, NTM Cr016750 ( MAGNT 31 ); 2 unsexed, NTM CR015864 ( MAGNT 31 ) .

Type locality. Utulau , Tongatapu, Tonga (~ 21°11ʹ24ʺS 175°16ʹ8.4ʺW) .

Description. Based on a male, 11.5 mm, AM P30115.

Head. Head eyes ovate; lateral cephalic lobe broad, truncated, anteroventral margin with notch/slit, anteroventral corner rounded. Antenna 1 longer than antenna 2; peduncular article 1 slightly shorter than article 2, with 3 robust setae along posterior margin; article 2 longer than article 3; accessory flagellum short, with 4 articles; flagellum with 17 articles. Antenna 2 peduncular article 4 slightly longer than article 5; flagellum with 7 articles. Mandible incisor a smooth cutting edge with 2 apicomedial cusps; accessory setal row with 3 setae; palp well developed, 3-articulate; article 1 about twice as long as broad, shorter than article 2, inner margin not produced distally; article 2 shorter than article 3; article 3 long (5 x as long as broad), weakly falcate, longer than article 1.

Pereon. Gnathopod 1 coxa anteroventral corner produced, rounded, anterior margin concave; merus without posterodistal tooth; carpus about 2 x as long as broad, subequal in length to propodus, setae in anterodistal bunches and along posterior margin; propodus palm acute, slightly convex, entire, defined by posterodistal corner, with posterodistal robust setae. Gnathopod 2 coxa posteroventral corner notch absent; basis slender; carpus compressed, projecting between merus and propodus, length 1 x breadth; propodus expanded, with slender setae along posterior margin, palm acute, straight, sculptured, palm about half length of propodus, with subtriangular distomedial shelf, with group of 8 robust setae on shelf, with midmedial excavation, margin lined with two rows of 10 robust setae, without teeth along margin, subpalmar surface smooth, without posteroventral corner, with 2 posterodistal robust setae; dactylus reaching end of palm, closing into socket, without setae on anterior margin, without posteroproximal shelf, apically subacute. Pereopod 4 coxa posteroventral lobe slightly developed, with rounded posteromedial corner. Pereopod 5 basis proximally expanded, slightly tapering distally, posterior margin straight, without long slender setae, posteroventral corner narrowly rounded; merus and carpus not broadened; carpus and propodus with few long, slender setae along anterior margin. Pereopod 6 basis posterior margin straight, without long slender setae, posteroventral corner narrowly rounded; merus and carpus not broadened; carpus and propodus with few long, slender setae along anterior margin; propodus expanded posterodistally to from a slight hood-like projection. Pereopod 7 basis posterior margin convex, minutely castelloserrate, without long slender setae, not produced posterodistally, posteroventral corner broadly rounded; merus and carpus not broadened; propodus expanded posterodistally to from a slight hood-like projection.

Pleon. Pleonites 1–3 dorsally smooth, without setae, spines or carinae. Epimeron 1 posteroventral corner subquadrate. Epimeron 2 posteroventral corner acute. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner with small acute spine. Urosomites 1–3 dorsally smooth, without setae, spines or carinae. Uropod 1 peduncle with basofacial robust seta. Uropod 3 rami distally rounded, apical robust setae long and short; inner ramus subequal in length to outer ramus; inner ramus long (length 2 to 2.5 x breadth); outer ramus long, length 2.9 x breadth, longer than peduncle, 1-articulate. Telson deeply cleft (more than 66%), longer than broad, tapering distally, each lobe with long inner and short outer apical cusp, apical conical extension reaching at least halfway along longest seta, without dorsal robust setae, each lobe with 2 short apical robust setae, without robust setae on inner or outer margins.

Female (sexually dimorphic characters). Based on female specimen, 7.1 mm, AM P30114. Gnathopod 2 carpus long, length 2 x breadth, not enclosed by merus and propodus; propodus subrectangular, palm extremely acute without corner, smooth, without shelf, without robust setae, without posteroventral corner.

Habitat. Marine, epibenthic.

Remarks. Myers (1986b) has established the similarity of E. alalo and E. pseudaffinis . Among species on the GBR, Elasmopus alalo is most similar to E. varanocephalensis from which it differs in having a midmedial excavation and two rows of setae along the palm of male gnathopod 2 (no midmedial excavation and one row in E. varanocephalensis ) and a smooth subpalmar surface (three raised round nodules in E. varanocephalensis ).

Distribution. Australia. Queensland: Thursday Island, Torres Strait (current study); Lizard Island ( Berents 1983); One Tree Island (current study). Northern Territory: New Year Island; McCluer Island; Oxley Island; Shell Islands (current study). Madagascar. Tuléar ( Ledoyer 1972). Mauritius. ( Ledoyer 1978). Micronesia. Marshall Islands (J.L. Barnard 1965). New Caledonia. I’îlot Maitre ( Ledoyer 1984). South China Sea: Nansha (or Spratly) Islands ( Ren 1998). Tonga. Utulau ( Myers 1986b).

Figures

FIGURE 1. Elasmopus alalo Myers 1988, male, 11.5 mm, AM P30115, Lizard Island, Great Barrier Reef.

FIGURE 2. Elasmopus alalo Myers 1988, male, 11.5 mm, AM P30115, female, 7.1 mm, AM P30114, Lizard Island, Great Barrier Reef.