Quadrimaera vallaris

Hughes, Lauren E., 2015, Maeridae from the Indo-Pacific: Elasmopus, Leeuwinella gen. nov., Maeropsis, Pseudelasmopus and Quadrimaera (Amphipoda: Crustacea), Zootaxa 4059 (2), pp. 201-256 : 247-249

Quadrimaera vallaris sp nov.

( Figs 44–46 )

Type material. Holotype male, 4.0 mm, dissected 3 slides, AM P.92505, dive site ‘The Wall’, Nepean Island, near Norfolk Island, 29°04'17"S, 167°57'40"E, 10 m, tufted red and brown algae, 15 May 2008, coll. J.K. Lowry, MI NFK 43.

Paratypes: male, 4.4 mm, dissected, 1 slide, AM P.92506; male, 4.0 mm, dissected, 1 slide, AM P.98702; 11 specimens, AM P.81504, same location as holotype.

Additional material examined. New Zealand. 1 specimen, AM P.90948, west side of South Meyer Island, Kermadec Islands, 29°14'47"S, 177°52'53"W, 10–12 m, rubble, 12 May 2011, coll. S.J. Keable, M.A. McGrouther and A. Reid, K 2011-3-2; 3 specimens, AM P.90949, Milne Islets, Raoul Island, Kermadec Islands, 29°16'57"S, 177°54'10"W, 22–27 m, tufting algae, 15 May 2011, coll. S.J. Keable, M.A. McGrouther and A. Reid, K 2011-23-4; 4 specimens, AM P.90950, Fishing Rock landing, Raoul Island, Kermadec Islands, 29°15'03"S, 17°754'12"W, 5 m, scrapings from rock wall, 17 May 2011, coll. S.J. Keableand A. Reid, K 2011-49 -7.

Type locality. Dive site ‘The Wall’, Nepean Island, near Norfolk Island, Tasman Sea, 29°4'17"S, 167°57'40"E.

Etymology. Latin for wall, in reference to the type locality.

Description. Of holotype male, 4.0 mm AM P.92505.

Head. Eyes ovate; lateral cephalic lobe broad, apically truncate, anteroventral margin with excavate, anteroventral corner acute. Antenna 1 longer than antenna 2; peduncular article 1 shorter than article 2, with 2 proximal robust setae on posterior margin; peduncular article 2 longer than article 3; flagellum articles as long as broad, or broader than long, with 13 articles; accessory flagellum long, more than half length of primary flagellum, with 7 articles. Antenna 2 peduncular article 4 longer than article 5; flagellum with 8 articles. Mandible accessory setal row, well developed with 4 setae; palp well developed, article 1 length twice width, shorter than article 2, inner margin weakly produced rounded; article 2 length 0.9 × article 3, lined with long slender setae; article 3 rectilinear, long, 2.8 × as long as broad, longer than article 1, with 5 lateral and 4 apical slender setae.

Pereon. Gnathopod 1 coxa anterior margin straight, anteroventral corner subquadrate, not produced, ventral margin without robust setae, posteroventral corner without notch; basis anterodistal corner without lobes; ischium anterodistal corner without lobes; merus with posteroventral corner subquadrate; carpus length 2.1 × width, 1.3 × propodus length, posterior margin lined with long setae, with rows of setae covering medial surface; propodus subovate, medial surface setal comb absent, palm subacute, weakly convex, entire, lined with slender setae, defined by posterodistal corner with 1 robust seta; dactylus closing along palm, unguis present. Gnathopod 2 subchelate; coxa posteroventral corner without notch, ventral margin without robust setae; basis broad, anterodistal corner with pair of well-developed lobes; ischium anterodistal corner with pair of well-developed lobes; merus with subacute posteroventral corner; carpus compressed, length 0.7 × width, anterior margin with 1 robust seta, posterior margin with a few slender setae; propodus quadrate, length 1.1 × width, posterior margin with clusters of long slender setae, palm length less than one third of propodus posterior margin, angle transverse, distal shelf subquadrate with 3 pairs of robust setae, palm with shallow rounded excavation, distal palm margin lined with robust setae, palm defined by posteroventral corner (90° angle, large subacute tooth and 1 robust seta; dactylus reach end of and closing along palm. Pereopods 3–4 coxa subquadrate; basis long, length 3 × width; merus, carpus and propodus not broadened; dactylus unguis bicuspidate. Pereopods 5–7 slender distally; basis rectilinear; merus, carpus and propodus slender, margins lined with a few long slender setae; dactylus unguis bicuspidate.

Pleon. Pleonites 1–3 dorsally smooth. Epimera 1–3 posterior and ventral margins smooth, posteroventral corner with acute tooth. Uropod 1 peduncle with 1 basofacial seta, length 1.4 × outer ramus; inner ramus slightly longer than outer ramus. Uropod 2 peduncle length subequal to outer ramus; inner ramus slightly longer than outer ramus. Uropod 3 peduncle 0.5 × inner ramus; inner ramus subequal to outer ramus, length 4 × width, apically truncate with long robust setae. Telson as long as broad, deeply cleft (80%), lobes divergent, not tapering distally, lobes apically truncate, each lobe with 5 apical robust setae.

Remarks. Quadrimaera vallaris sp. nov. has a plain gnathopod 2 palm without teeth or deep excavations and, 5 apical setae on telson similar to Q. schellenbergi ( Ruffo, 1938) . The exceptionally long rami of uropod 3, length 4 times the breadth, distinguished this species from Q. schellenbergi and other Quadrimaera species. Although uropod 3 length is known to variable with growth stage (Krapp-Schickel 2009), the length of rami in Q. vallaris sp. nov. is exceptionally elongate distinguishing it from currently known species. The male figured here is 4.0 mm, so it is possible that the palm development is not that of a terminal male given the relatively propodus palm sculpturing and lack of sinus or tooth on the dactylus posterior margin.

Distribution. South Pacific Ocean: Tasman Sea: Norfolk Island; New Zealand: Kermadec Islands (current study).

Figures

FIGURE 44. Quadrimaera vallaris sp. nov. holotype male 4.0 mm, AM P. 92505, dive site ″ the Wall ″, Nepean Island near Norfolk Island.

FIGURE 45. Quadrimaera vallaris sp. nov. holotype male 4.0 mm, AM P. 92505, dive site ″ the Wall ″, Nepean Island near Norfolk Island, scales 0.1 mm.

FIGURE 46. Quadrimaera vallaris sp. nov. paratype male 4.0 mm, AM P. 98702, dive site ″ the Wall ″, Nepean Island near Norfolk Island, scales 0.1 mm.