Mallacoota scopulosa, Lowry & Hughes, 2009

Lowry, J. K. & Hughes, L. E., 2009, Maeridae, the Elasmopus group *, Zootaxa 2260 (1), pp. 643-702 : 687-690

Mallacoota scopulosa sp. nov.

( Figs 25 , 26 )

Type material. Holotype, 1 male, 7.3 mm, 4 slides, AM P78042, Steves bommie, near Two Trees Islet, outer reef, One Tree Island , Queensland (23°29.059’S 152°5.452’E), coral rubble with algae, 13.2 m, L.E. Hughes & J.K. Lowry, 27 October 2006 ( QLD 1974 ) . Paratype: 1 female, 7.7 mm, 1 slide, AM P78043 ( QLD 1974 ); 1 unsexed, AM P78044 ( JDT / LIZ 13 ); many unsexed, AM P75627 ( QLD 1972 ); 5 unsexed, AM P75746 ( QLD 1973 ); 2 unsexed, AM P75757 ( QLD 1974 ); many unsexed, AM P75747 ( QLD 1974 ); 7 unsexed, AM P75749 ( QLD 1976 ); 2 unsexed, AM P75750 ( QLD 1977 ); many unsexed, AM P75628 ( QLD 1983 ); 1 unsexed, AM P75759 ( QLD 2001 ); 12 unsexed, AM P75758 ( QLD 2003 ) .

Type locality. Steves bommie, near Two Trees Islet, outer reef, One Tree Island , Queensland (23°29.059’S 152°5.452’E), coral rubble with algae, 13.2 m .

Etymology. Named from the Latin ‘scopulosa’ for the hard rocky-rubble bottom where it is found.

Description. Based on holotype, male, 7.3 mm, AM P78042.

Head. Head eyes ovate; lateral cephalic lobe broad, rounded, anteroventral margin with notch/slit, anteroventral corner rounded. Antenna 1 peduncular article 1 subequal in length to article 2; accessory flagellum minute, with 2 articles. Mandible incisor a smooth cutting edge with 2 apicomedial cusps; accessory setal row with 3 setae; palp reduced, 3-articulate; article 1 about twice as long as broad, shorter than article 2, inner margin article 1 not produced distally; article 2 longer than article 3; article 3 short (about 3 x as long as broad), rectolinear, 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, carpus subequal in length to propodus (length 1.2 x propodus), setae in anterodistal bunches and along posterior margin; propodus palm acute, straight, entire, defined by posterodistal corner, with posterodistal robust setae. Gnathopod 2 coxa posteroventral corner notch absent; basis slender; merus with rounded distoventral corner; carpus compressed, projecting between merus and propodus, length 0.8 x breadth; propodus expanded, without setal bunches along posterior margin, palm acute, convex, sculptured, palm about half length of propodus, with subtriangular distomedial shelf, with group of 6 robust setae on shelf, with midmedial excavation, palmar margin without robust setae, with 2 palmar teeth, subpalmar surface smooth, corner defined by posteroventral tooth, without posterodistal robust setae; dactylus reaching end of palm, closing along palm, without setae on anterior margin, with posteroproximal shelf, apically falcate. Pereopod 4 coxa posteroventral lobe slightly developed, with rounded posteromedial corner. Pereopod 5 basis expanded, posterior margin subsigmoidal, without long slender setae, posteroventral corner broadly rounded; carpus and propodus with few long, slender setae along anterior margin. Pereopod 6 basis posterior margin straight, without long slender setae, minutely castelloserrate, posteroventral corner broadly rounded; carpus and propodus with few long, slender setae along anterior margin; merus and carpus broadened; propodus expanded posterodistally to from a hood-like projection. Pereopod 7 basis posterior margin slightly convex, minutely castelloserrate, without long slender setae, not produced posterodistally, posteroventral corner broadly rounded; merus and carpus broadened; propodus expanded posterodistally to from a hood-like projection.

Pleon. Pleonites 1–3 dorsally smooth, without setae, spines or carinae. Epimeron 1 posteroventral corner with small acute spine. Epimeron 2 posteroventral corner strongly produced, acute. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner with produced acute spine. Urosomite 1 bicarinate, subtriangular. Urosomites 2–3 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 subequal in length to outer ramus; inner ramus short (length 1 to 1.9 x breadth); outer ramus short (length 2 x breadth), subequal to peduncle, 1-articulate. Telson deeply cleft (more than 66%), broader than long, slightly tapering distally, apical margins concave, 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 and outer margins.

Female (sexually dimorphic characters). Based on female, 7.7 mm, AM P78043. Gnathopod 2 carpus long, length 1.7 x breadth, not enclosed by merus and propodus; straight, one third length of propodus, smooth, without distomedial shelf, with posterodistal robust setae; dactylus apically acute, without posteroproximal shelf.

Habitat. Marine, epibenthic.

Remarks. Mallacoota scopulosa is a large species, nearly twice the size of similar species such as the western Indian Ocean species M. subinsignis Ledoyer, 1979b and M. magnimerus Appadoo & Myers, 2006 . It differs from M. subinsignis in the coxa of gnathopod 1 which has no posterodistal notch (well developed in M. subinsignis ); in the palm of gnathopod 2 which has a well developed subtriangular shelf (oblique and weakly developed in M. subinsignis ) two palmar teeth and a well developed corner tooth (one palmar tooth, a well developed corner tooth and a notch along the posterior margin in M. subinsignis ); and in the dactylus of gnathopod 2 which is strongly falcate (apically acute in M. subinsignis ). Mallacoota magnimerus is distinguished from M. scopulosa Appadoo & Myers, 2006 by its immensely broadened meri on pereopods 6– 7. On the GBR only M. scopulosa , M. chandaniae and M. capricornia have the corner of the male gnathopod 2 palm defined by a tooth. Of these three species only M. scopulosa has a falcate tip on the dactylus of male gnathopod 2 and two short apical robust setae on each lobe of the telson.

Distribution. Australia. Queensland: Lizard Island; One Tree Island (current study).

Figures

FIGURE 25. Mallacoota scopulosa sp. nov., male, 7.3 mm, AM P78042, One Tree Island, Great Barrier Reef.

FIGURE 26. Mallacoota scopulosa sp. nov., male, 7.3 mm, AM P78042, female, 7.7 mm, AM P78043, One Tree Island, Great Barrier Reef.