Maeridae, the Elasmopus group * Author Lowry, J. K. Author Hughes, L. E. text Zootaxa 2009 2009-10-08 2260 1 643 702 https://www.biotaxa.org/Zootaxa/article/view/zootaxa.2260.1.33 journal article 10.11646/zootaxa.2260.1.33 1175-5326 5361655 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. 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. 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 ).