Elasmopus spinicarpus Berents, 1983

Lowry, J. K. & Hughes, L. E., 2009, Maeridae, the Elasmopus group *, Zootaxa 2260 (1), pp. 643-702 : 663-666

Elasmopus spinicarpus Berents, 1983

( Figs 11 , 12 )

Elasmopus spinicarpus Berents, 1983: 121 , figs 17–19. — Springthorpe & Lowry, 1994: 31 (catalogue). — Lowry & Stoddart, 2003: 178 (catalogue).

Material examined. Holotype male, 8.5 mm, AM P30212 ( QLD 39 ); paratype, female, 5.4 mm, AM P30213 ( QLD 39 ); 3 unsexed, AM P75732 ( QLD 1949 ); 3 unsexed, AM P75730 ( QLD 1959 ); 13 unsexed, AM P75729 ( QLD 1988 ); many unsexed, AM P75731 ( QLD 2006 ).

Type locality. Casuarina Beach , Lizard Island, Great Barrier Reef, Australia (14°40.5'S 145°26.6'E) .

Description. Based on holotype male, 8.5 mm, AM P30212.

Head. Head eyes ovate; lateral cephalic lobe broad, truncated, anteroventral margin with notch/slit, anteroventral corner subquadrate. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, with 1 distal robust seta on posterior margin; accessory flagellum short, with 3 articles; flagellum with about 17 articles. Antenna 2 peduncular article 4 as long as article 5; flagellum with 8 articles. Mandible incisor a smooth cutting edge with 2 apicomedial cusps; accessory setal row with 4 setae; palp well developed, 3-articulate; article 1 about twice as long as broad, shorter than article 2, inner margin article 1 not produced distally; article 2 subequal to article 3; article 3 short (about 2 x as long as broad), strongly falcate, longer than article 1.

Pereon. Gnathopod 1 coxa anteroventral corner weakly produced, rounded, anterior margin straight; merus without posterodistal tooth; carpus about 2 x as long as broad, slightly longer than propodus, setae covering surface; propodus palm acute, convex, entire, defined by posterodistal corner, with posterodistal robust setae. Gnathopod 2 coxa posteroventral corner notch absent; basis slender; merus with subquadrate distoventral corner; carpus compressed, projecting between merus and propodus, length 1 x breadth; propodus expanded, with slender setae along posterior margin, palm acute, convex, smooth, palm about one third length of propodus, without distomedial shelf, without group of robust setae in shelf area, palmar margin lined with a row of 5 robust setae, without teeth, subpalmar surface smooth, without posteroventral corner, with 2 posterodistal robust setae; dactylus reaching end of palm, closing along palm, without setae on anterior margin, without posteroproximal shelf, apically subacute. Pereopod 4 coxa posteroventral lobe well developed, with subrectangular posteromedial corner. Pereopod 5 basis proximally expanded, tapering distally, posterior margin straight, without long slender setae, posteroventral corner narrowly rounded or subquadrate; carpus and propodus without long, slender setae along anterior margin. Pereopod 6 basis posterior margin straight, without long slender setae, posteroventral corner narrowly rounded; carpus and propodus without long, slender setae along anterior margin; merus and carpus not broadened; propodus not expanded posterodistally. Pereopod 7 basis posterior margin convex, smooth, without long slender setae, not produced posterodistally, posteroventral corner broadly rounded; merus and carpus not broadened; propodus not expanded posterodistally.

Pleon. Pleonites 1–3 dorsally smooth, without setae, spines or carinae. 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 truncated, apical robust setae long or short; inner ramus subequal in length to outer ramus; inner ramus long (length 2 to 2.5 x breadth); outer ramus long, length 2.4 x breadth, longer than peduncle, 1- articulate. Telson deeply cleft (more than 66%), about as long as broad, tapering distally, lobes truncated with lateral apical cusps extending about halfway along longest seta, without dorsal robust setae, each lobe with 3 short apical robust setae, without robust setae on inner and outer margins.

Female (sexually dimorphic characters). Paratype, female, 5.4 mm, AM P30213. Gnathopod 2 smaller and less robust than that of male; carpus short, not lobate, not enclosed by merus and propodus, length 2 x breadth; propodus without sparse setal bunches along posterior margin, palm straight, palmar margin with sparse robust setae, defined by posteroventral corner, with posterodistal robust setae .

Habitat. Marine, epibenthic, living under stones near low tide mark and in association with the ophiuroid Ophiocoma scolopendrina ( Lamarck, 1816) .

Remarks. This is the first report of E. spinicarpus since its original description by Berents (1983). The new records extend the distribution of the species from Lizard Island in the northern part of the GBR to One Tree Island towards the southern end.

Elasmopus spinicarpus Berents, 1983 is possibly the sister species to E. seticarpus Myers, 1985 . Both species have short strongly falcate third articles on the mandibular palp, long telson with short apical setae and relatively simple palm on the male second gnathopods. However the carpus of E. spinicarpus , although strongly setose, is much less so than that of E. seticarpus .

On the GBR E. spinicarpus is similar to E. alalo and E. varanocephalensis , based on the elongate, deeply cleft telson. Elasmopus spinicarpus differs from the latter species in having a strongly falcate third article on the mandibular palp; a straight anterior margin on the first coxa; and rows of short, medial, slender setal on the male gnathopod 2 propodus and expanded carpus.

Distribution. Australia. Queensland: Lizard Island ( Berents 1983); One Tree Island (currently study).

Figures

FIGURE 11. Elasmopus spinicarpus Berents 1983, holotype, male, 8.5 mm, AM P30212, Lizard Island, Great Barrier Reef.

FIGURE 12. Elasmopus spinicarpus Berents 1983, holotype, male, 8.5 mm, AM P30212, paratype, female, 5.4 mm, AM P30213, Lizard Island, Great Barrier Reef.