Elasmopus crenulatus Berents, 1983

Lowry, J. K. & Hughes, L. E., 2009, Maeridae, the Elasmopus group *, Zootaxa 2260 (1), pp. 643-702 : 649-652

Elasmopus crenulatus Berents, 1983

( Figs 3 , 4 )

Elasmopus crenulatus Berents, 1983: 113 , figs 10–12. — Springthorpe & Lowry, 1994: 13 (catalogue). — Lowry & Stoddart, 2003: 178 (catalogue).

Material examined. Holotype, male, 3.5 mm, AM P30095 (76 LIZ B 6.18.3); paratype, female, 4.8 mm, AM P30096 (76 LIZ B 6.2 ); 1 unsexed, AM P70573 ( QLD 1618 ); 2 unsexed, AM P 71604 ( QLD 1621 ); 1 unsexed, AM P70611 ( QLD 1621 ); 10+ unsexed, AM P 70596 ( QLD 1622 ); 6 unsexed AM P70988 ( QLD 1649 ); 1 unsexed, AM P71603 ( QLD 1670 ); 10+ unsexed, AM P70851 ( QLD 1689 ); 6 unsexed, AM P70982 ( QLD 1693 ); 1 male, 4.4 mm, 3 slides, AM P78025 ( QLD 1698 ); 1 male, 4.8 mm, AM P78026 ( QLD 1698 ); 10+ unsexed, AM P70929 ( QLD 1698 ); 1 unsexed, AM P71011 ( QLD 1705 ); 5 unsexed, AM P 71021 ( QLD 1709 ); 7 unsexed, AM P71045 ( QLD 1711 ); 2 unsexed, AM P71040 ( QLD 1715 ); 1 unsexed, AM P71087 ( QLD 1716 ); 10+ unsexed, AM P71181 ( QLD 1730 ); 1 unsexed, AM P71275 ( QLD 1770 ); 10+ unsexed, AM P75712 ( QLD 1963 ); 10+ unsexed, AM P75714 ( QLD 1967 ); 6 unsexed, AM P75713 ( QLD 2006 ); 1 male, NTM Cr016749 ( MAGNT 20 ).

Type locality. Off Chinamans Ridge , Watsons Bay, Lizard Island, Queensland, Australia (14°40'S 145°27'E) .

Description. Based on holotype male, 3.5 mm, AM P30095 ( Berents, 1983).

Head. Head eyes ovate; lateral cephalic lobe broad, truncated, apically rounded, anteroventral margin with notch/slit, anteroventral corner rounded. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, with 1 robust seta on posterior margin; accessory flagellum minute, with 1 article; flagellum with 8 articles. Antenna 2 peduncular article 4 subequal to article 5; flagellum with 6 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 not produced distally; article 2 subequal to article 3; article 3 short (2.3 x as long as broad), strongly 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, straight, entire, defined by posterodistal corner, with posterodistal robust seta. Gnathopod 2 coxa posteroventral corner notch absent; basis slender; merus with subquadrate distoventral corner; carpus compressed, not enclosed by merus and propodus, length 0.7 x breadth; propodus expanded, with dense slender setae along posterior margin, palm acute, convex, smooth, with subtriangular distomedial shelf, with group of 3 robust setae on shelf, palmar margin without robust setae, without teeth, subpalmar surface smooth, without posteroventral corner, without posterodistal robust setae; dactylus closing along palm, without setae on anterior margin, without posteroproximal shelf, apically subacute. Pereopod 4 coxa posteroventral lobe absent, posterior margin concave. Pereopod 5 basis proximally expanded, tapering distally, posterior margin slightly subsigmoidal, without long slender setae, posteroventral corner narrowly rounded or subquadrate; 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; carpus and propodus without long, slender setae along anterior margin; merus and carpus broadened; propodus not expanded posterodistally. Pereopod 7 basis posterior margin convex, castelloserrate, without long slender setae, not produced posterodistally, posteroventral corner narrowly rounded; merus and carpus broadened; propodus not expanded posterodistally.

Pleon. Pleonites 1–3 dorsally smooth, without setae, spines or carinae. Epimeron 1 posteroventral corner with small acute spine. 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 truncated, apical robust setae long; inner ramus slightly shorter than outer ramus; inner ramus short (length 1.7 x breadth); outer ramus short, shorter than peduncle, 1-articulate. Telson moderately cleft (30 to 65%), broader than long, short, lobes apically truncated, without apical conical extensions, without dorsal robust setae, each lobe with 3 long and short apical robust setae, without robust setae on inner and outer margins.

Female (sexually dimorphic characters). Based on paratype, female, 4.8 mm, AM P30096. 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 .

Habitat. Marine, epibenthic, living on reef rock, dead coral and encrusting algae in 4 to 7 m depth.

Remarks. This is the first record of E. crenulatus since the original description by Berents (1983). It is most probably the sister species of E. arrawarra Hughes & Lowry (2006) from the Solitary Islands. Elasmopus crenulatus and E. arrawarra have a disjunct distribution along the east coast of Australia. Both species have shortened first and second antennae, a short article 3 on the mandibular palp, a short inner ramus on uropod 3 and an almost subquadrate telson with strong apical robust setae.

Elasmopus crenulatus can be distinguished from other species on the GBR by the basis of pereopod 7 with its strongly crenulate posterior margin, by the short inner ramus on uropod 3 and the short, almost subquadrate telson with strong, apical robust setae.

Distribution. Australia. Queensland: Lizard Island ( Berents 1983; current study); One Tree Island (current study). Northern Territory: Darwin (current study). Indian Ocean. Cocos (Keeling) Islands ( Berents 1983).

Figures

FIGURE 3. Elasmopus crenulatus Berents 1983, habitus male, 4.4 mm, AM P78025, Lizard Island, parts holotype male, 3.5 mm, AM P30095, Lizard Island, Great Barrier Reef.

FIGURE 4. Elasmopus crenulatus Berents 1983, Holotype male, 3.5 mm, AM P30095, paratype, female, 4.8 mm, AM P30096, Lizard Island, Great Barrier Reef.