Maeraceterus bramblensis

Hughes, Lauren E., 2016, New genera, species and records of Maeridae from Australian Waters: Austromaera, Ceradocus, Glossomaera, Hamimaera, Huonella gen. nov., Linguimaera and Maeraceterus gen. nov. (Crustacea: Amphipoda), Zootaxa 4115 (1), pp. 1-81 : 72-75

Maeraceterus bramblensis gen. et sp. nov.

( Figs 60–62 )

Type material. Holotype male, 5.1 mm, dissected, 4 slides, AM P.79457, Princess Royal Harbour , Bramble Point, Western Australia (35°2'S 117°55' E), 1–1.5 m, on seagrass Poisidonia australis , diver held corer, January 1988, coll. P. Hutchings and party.

Additional material examined. Tasmania: 1 male, dissected, 4 slides, AM P. 97857, North East River (39°46′S 147°58′E), depth unknown, 8 May 1997, coll. A. Davey ( CAM 78 ) ; 1 b female, dissected, 1 slide, AM P.88467, North East River (39°46′S 147°58′E), depth unknown, 8 May 1997, coll. A. Davey ( CAM 78 ) .

Type locality. Princess Royal Harbour , Bramble Point, Western Australia (35°2′S 117°55′ E).

Etymology. Named from the type locality.

Description. Based on holotype male, 5.1 mm, AM P.79457.

Head. Eyes ommatidea scattered; lateral cephalic lobe broad, apically rounded, anteroventral margin with notch/slit, anteroventral corner truncate. Antenna 1 longer than antenna 2; peduncular article 1 shorter than article 2, with 1 robust seta posterodistally; peduncular article 2 longer than article 3; flagellum articles as long as broad, with 16 articles; accessory flagellum short, significantly less than half length of primary flagellum, with 3 articles. Antenna 2 peduncular article 4 longer in length than article 5; flagellum with 10 articles. Mandible accessory setal row, well developed with 5 setae; palp well developed, article 1 length 0.9 × width, shorter than article 2; article 2 longer than article 3, with a few slender setae; article 3 rectilinear, long, 3.5 × as long as broad, longer than article 1, with 3 apical slender setae. Lower lip lobes without apical ducts; mandibular lobes apically rounded. Maxilla 1 inner plate with 3 apical plumose setae; outer plate palp with apical slender setae.

Pereon. Gnathopod 1 coxa anterior margin concave, anteroventral corner produced, subacute, posteroventral corner without notch; merus with posteroventral corner subquadrate; carpus length twice width, 1.3 × propodus length, without rows of short medial setae; propodus rectilinear, medial surface setal comb absent, palm subacute, weakly convex, entire, with weakly defined posterodistal corner; dactylus closing along palm.

Gnathopod 2 symmetrical, subchelate; coxa posteroventral corner without notch; basis broad, anterodistal corner with pair of well-developed rounded lobes; ischium anterior margin with pair of well-developed lobes; merus with subacute posteroventral corner; carpus compressed, length 0.9 × width, posterior margin with long slender setae; propodus subovate, length 1.8 × width, posterior margin with clusters of long slender setae, palm angle subacute, posterodistal shelf subrectangular, margin sculpted, with 4 rounded teeth, palm weakly defined with small rounded tooth, without robust setae; dactylus closing along and reaching end of palm.

Pereopod 4 coxa without posterodistal lobe. Pereopods 5–7 slender distally; basis posteriorly expanded, margin weakly convex, without long slender setae; merus and carpus slightly broadened; dactylus unguis simple. Pereopod 6 basis larger than pereopod 7.

Pleon. Pleonites 1–3 dorsally smooth. Epimera 1–3 posterior margin smooth, corner with small tooth. Urosomites 1–3 without carina. Uropod 1 peduncle with 1 basofacial seta; rami subequal, 0.9 × peduncle length. Uropod 2 peduncle length 0.8 × outer ramus; inner ramus longer than outer ramus. Uropod 3 unknown. Telson deeply cleft, length subequal to width, lobes weakly divergent, tapering distally, lobes apical margins concave, each lobe with 3 apical and 1 lateral pair of robust setae.

Remarks. Maeraceterus bramblensis gen. et sp. nov. differs from M. taaroa gen. et sp. nov. in the number of teeth on the male gnathopod 2 palm and the absence of a palm defining robust setae which is present in the latter species. In M. bramblensis the ischium is without robust setae while M. taaroa has a well-developed row of long robust setae on the posterior margin.

Maeraceterus bramblensis has the unusual state of pereopod 6 basis being larger than that of the pereopod 7 basis (observed on both left and right sides of the holotype). This character is not observed in M. taaroa and therefore is considered a species rather than generic level character.

Distribution. Australia. Western Australia: Bramble Point (current study). Tasmania: North East River (current study).

Figures

FIGURE 60. Maeraceterus bramblensis gen. et sp. nov., holotype male, 5.1 mm, AM P. 79457, Bramble Point, Western Australia.

FIGURE 61. Maeraceterus bramblensis gen. et sp. nov., holotype male, 5.1 mm, AM P. 79457, Bramble Point, Western Australia, scales 0.1 mm.

FIGURE 62. Maeraceterus bramblensis gen. et sp. nov., holotype male, 5.1 mm, AM P. 79457, Bramble Point, Western Australia, scales 0.1 mm.