Mallacoota maridwinae, Hughes, 2011

HUGHES, L. E., 2011, New species of Hoho, Mallacoota and Parelasmopus (Maeridae: Amphipoda) from Australian waters, Zootaxa 2955 (1), pp. 1-79 : 51-54

Mallacoota maridwinae sp. nov.

( Figs 31–33 )

Type material. Holotype: male, 11.0 mm, dissected, 4 slides, AM P.85217 . Paratypes: 2 females, AM P.77498, Boat Harbour, south of Port Stephens , New South Wales (32°46'59"S 152°06'E), 2 m, by hand on snorkel, mixed red coralline algae, 14 March 2006, coll. M. Capa and C. Fraser ( NSW 2985 ) .

Additional material examined. 1 male, 8.8 mm, dissected, 1 slide, AM P.85218; 1 male, 7.0 mm, dissected,1 slide, AM P.85219; 1 male, 4.8 mm, dissected,1 slide, AM P.85220; 1 female specimen, AM P.85221, Diggers Camp Beach , (29°49’S 153°17’E), coll. G.J. Edgar (no further data) .

Type locality. Boat Harbour, south of Port Stephens , New South Wales (32°46'59"S 152°06'E) .

Etymology. Derived from the names of the collectors of the type material, Maria Capa and Ceridwin Fraser.

Description. Based on holotype, male, 11.0 mm, AM P.85217.

Head. Eyes ovate; lateral cephalic lobe broad, rounded, anteroventral margin with notch/slit. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, without robust setae along posterior margin; article 2 longer than article 3; flagellum articles longer than broad, with 23+ articles; accessory flagellum minute, with 2 articles. Antenna 2 peduncular article 2 cone gland not reaching to end of peduncular article 3; article 4 subequal in length to article 5; flagellum with 9 articles. Maxilla 1 inner plate subtriangular, with 2 apical plumose setae. Lower lip outer lobes with two pair of ducts, mandibular lobes apically subacute. Mandible accessory setal row well developed with 4 setae; molar well developed, triturative; mandibular palp well developed, 3-articulate; article 1 three times as long as broad, shorter than article 2; article 2 subequal to article 3 without setae; article 3 rectolinear, long (5 times as long as broad), longer than article 1, with 2 apical setae.

Pereon. Gnathopod 1 coxa anterior margin concave, anteroventral corner produced, rounded; carpus about twice as long as broad, subequal in length to propodus; propodus medial surface with comb, palm acute, convex, entire, defined by posterodistal corner with 2 robust setae. Gnathopod 2 subchelate; basis broad; anterodistal corner subquadrate; merus acutely produced distoventrally; carpus compressed, lobate, projecting between merus and propodus; propodus massive, without sparse setal bunches along posterior margin, palm acute, straight, smooth, about half length of propodus, subtriangular distomedial shelf, with 5 robust setae on shelf, palmar margin lined with a row of robust setae, without posterodistal robust setae, subpalmar surface with subtriangular tooth; dactylus with posteroproximal shelf, apically subacute, closing into socket. Pereopod 4 coxa posteroventral lobe well developed, with subrectangular posteromedial corner. Pereopods 5–7 broad distally; basis expanded, posterior margin minutely castelloserrate, without long slender setae; merus and carpus broadened; carpus and propodus without long, slender setae along posterior margin; propodus not expanded posterodistally;

dactylar ungues simple. Pereopod 5 basis posterior margin straight, posteroventral corner broadly rounded. Pereopods 6–7 basis posterior margin convex, posteroventral corner broadly rounded. Pereonite 7 without carina.

Pleon. Pleonites 1–3 without carina. Epimera 1–2 posteroventral corner with small acute tooth. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner produced acute. Urosomite 1 bicarinate, subtriangular. Urosomites 2–3 without carina. Uropod 1 peduncle with 1 basofacial seta; outer ramus slightly shorter than inner ramus. Uropod 2 outer ramus slightly shorter than inner ramus. Uropod 3 rami distally truncated, Remarks. Mallacoota maridwinae sp. nov. has the male gnathopod 2 propodus palm entire and unsculpted, similar to M. balara , M. latibrachium , M. odontoplax and M. latibrachoides . These species also have pereopods 5– 7 with expanded basis and broad merus and carpus, as well as the uropod 3 rami short. Mallacoota maridwinae sp. nov. can be distinguish from all Mallacoota species by the combination of the male gnathopod 2 propodus palm smooth and margin lined with robust setae.

The type material from Port Stephens, collected as a single male specimen of 11.0 mm length, differs from the sequence of males from Diggers Beach, body sizes from 4.8–8.8 mm, in the presence of a subpalmar tooth near the distomedial shelf. In all other characters, including the gnathopod 2 form, pereopods 5–7 basis, setation and telson, the material is similar. For these reasons I am grouping these four individuals as the same species.

Distribution. New South Wales: Port Stephens; Diggers Beach (current study).

Figures

FIGURE 31. Mallacoota maridwinae sp. nov. holotype male, 11.0 mm, AM P.85217, Port Stephens, New South Wales.

FIGURE 33. Mallacoota maridwinae sp. nov. ‘a’ male, 4.8 mm, AM P.85220; ‘b’ male, 7.0 mm, AM P.85219; ‘c’ male, 8.8 mm, AM P.85218, Diggers Beach, New South Wales.