Mallacoota petriei Thomson 1882
Creators: name: Kilgallen, Niamh M.
name: Ahyong, Shane T.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Melitidae
Mallacoota
Mallacoota petriei

description: Mallacoota petriei (Thomson, 1882) comb. et stat. nov.
(Figs 5–8)
Moera petriei Thomson, 1882: 236, pl. 18, fig. 3.
Moera subcarinata. — Chilton 1885b: 368 [Stewart Island specimens].
Elasmopus subcarinatus. — Chilton 1915: 321, figs 1–4 [“form 1”]. — Stebbing 1906: 441 (in part; part M. subcarinata Haswell).
Maera subcarinata. — Hurley 1954: 603 (list, in part).
Not Moera petriei. — Chilton 1883: 82 (= Mallacoota chiltoni sp. nov.).
Type material. Neotype male (9.0 mm), NIWA 69791, Bluff, New Zealand, 46°35.656’S, 168°20.377’E, 3 m, 2BLU064, 14 Feb 2006.
Other material examined. Te Miko Reef, Bay of Islands: 1 female (6.0 mm), 1 male (10.5 mm), NIWA 69792, 35º13.73’S, 174º11.00’E, 8–11 m RHO1257, coll. B. Crocker & R. D’Archino, 20 Sep 2010; 1 female (10.5 mm), NIWA 69793, 35º13.73’S, 174º11.00’E, 10 m RHO1314, coll. B. Crocker & R. D’Archino, 21 Sep 2010; 1 female (10.0 mm), NIWA 69794, 35º13.73’S, 174º11.00’E, 10 m, RHO1306, coll. B. Crocker & R. D’Archino, 21 Sep 2010; 3 males (9.0– 10.5 mm), 2 females (6.0–7.0 mm), NIWA 69795, Bay of Islands, 35º14.11’S, 174º09.69’E, LIN09305, ROB; 1 male (12.5 mm), NIWA 69796, 35º13.73’S, 174º11.00’E, 8–11.5 m, RHO110, coll R. D’Archino & R. Stewart, 0 8 Feb 2010; 1 male (14.0 mm), NIWA 69797, 35º13.73’S, 174º11.00’E, 8–11.5 m, RHO0503, coll. R. D’Archino & S. Miller, 10 Feb 2010. Bluff: 1 female (9.0 mm), 1 male (6.0 mm), NIWA 69798, 46°35.656’S, 168°20.377’E, 3 m, 2BLU064, 14 Feb 2006; 1 juvenile (6.0 mm), NIWA 69799, 46°35.796’S, 168°20.561’E, 7 m, 2BLU040, 14 Feb 2006; 1 female (7.5 mm), NIWA 69800, 46°35.656’S, 168°20.377’E, 7 m, 2BLU071, 14 Feb 2006; 2 females (7.0–13.0 mm), MITS 3828, 46°35.847’S, 168°20.727’E, 7 m, 2BLU008, 13 Feb 2006; 1 female (8.0 mm), MITS 3791, 46°35.880’S, 168°20.732’E, 3 m, 2BLU107, 15 Feb 2006; 1 female (5.0 mm), MITS 3800, 46°35.484’S, 168°20.976’E, 0 m, 2BLU090, 15 Feb 2006; 2 juveniles (5.5– 6.0 mm), MITS 3811, 46°35.847’S, 168°20.727’E, 3 m, 2BLU010, 13 Feb 2006; 1 female (8.0 mm), MITS 3806, 46°35.484’S, 168°20.976’E, 2 m, 2BLU087, 15 Feb 2006; 1 male (8.0 mm), 3 females (4.5–7.0 mm), MITS 3795, 46°35.76’S, 168°20.405’E, from wharf pile at 3 m over 10 depth, 2BLU061, 14 Feb 2006; 1 juvenile, 6.0 mm, 1 female, 9.0 mm, MITS ex3803, 46°35.656’S, 168°20.377’E, 3 m, 2BLU072, 14 Feb 2006.
Milford Sound: female (4.0 mm), MITS 27677, 44°35.187’S, 167°47.334’E, pile scrape at 3 m, bottom depth 16 m, MFN448, 10 Jun 2006.
Diagnosis. Coxae 1–3 with posteroventral notch. Gnathopod 2 (male) propodus massive, moderately hirsute medially, slightly concave anterodistally, straight posteriorly; palm irregular; dactylus falcate. Pereopods 5–6 basis posterior margin slightly concave, pereopod 7 rounded posteriorly.
Description of neotype. Body laterally compressed. Head with notch below lateral cephalic lobe, rostrum absent. Eyes oval. Antenna 1 longer than antenna 2; peduncle article 1 broader than and subequal in length to article 2, with 3 robust setae along ventral margin (1 distal, 2 proximal); article 2 slender, much longer than article 3; primary flagellum 29-articulate, article 1 twice as long as broad; accessory flagellum with 4 articles, article 4 minute. Antenna 2 peduncle article 4 longer than article 5; flagellum article 1 longer than following articles.
Upper lip broader than long, entire. Mandibles with weakly triturative molars; palp 3-articulate, article 3 with 2 terminal setae; left incisor 2-toothed, lacinia mobilis 4-toothed; right incisor smooth, lacinia mobilis 8-toothed (based on female NIWA 69798). Lower lip with inner lobes well developed; outer lobes with 1 large and 1 small spine-like process, each apparently with distal pore. Maxilla 1 with 2-articulate palp; inner plate with 2 terminal plumose setae. Maxilla 2 plates slender with apical simple setae; outer plate with sub-apical plumose setae. Maxilliped palp 4-articulate; outer plate not reaching distal end of palp article 2, with numerous robust setae along inner and distal margins; inner plate shorter than outer plate with plumose setae along margins.
Gnathopod 1 subchelate; coxa anterior margin slightly concave, posteroventral corner with notch; carpus subequal in length to propodus; propodus suboval, with transverse rows of setae on inner surface; palm acute, slightly convex, defined by 2 robust setae posteriorly; dactylus slender.
Gnathopod 2 massive, subchelate; coxa posteroventral corner with notch; basis with anterodistal lobe; merus sharply produced posterodistally; carpus short, propodus enlarged and oblong, slightly concave along anterodistal margin, hirsute along posterior and medial margins; palm poorly-defined, irregularly sculptured with distomedial shelf, large mid-medial and small proximal blunt teeth; dactylus curved, falcate, irregularly sculptured along occlusal margin.
Pereopods 3–7 dactyli with unguis tapering to acute apex. Pereopod 5 smaller than pereopods 6–7; coxa slightly more produced posteriorly; basis posterior margin concave. Pereopod 6 basis narrow, posterior margin concave. Pereopod 7 basis rounded posteriorly. Gills present on gnathopod 2 to pereopod 6.
Epimera 1 and 2 posteroventral corners produced into small spine. Epimeron 3 posteroventral corner acutely produced into large wide spine.
Urosomite 1 dorsally bicarinate. Uropods strongly armed with robust setae. Uropod 1 peduncle with a basofacial seta; inner ramus slightly longer than outer ramus. Uropod 2 peduncle subequal in length to rami; inner ramus slightly longer than outer ramus. Uropod 3 peduncle much shorter than rami; rami subequal in length. Telson about as long as broad; deeply cleft (>66%); apices acutely bifid, with longer outer and shorter inner apical conical extensions and with 3 long robust setae
Description of female (sexually dimorphic characters). Based on female, 9.0 mm, NIWA 69798. Gnathopod 2 subchelate, not enlarged; basis lacking anterodistal lobe; merus posterodistally produced; carpus slightly shorter than propodus; propodus palm acute, slightly convex. Oostegites slender, from gnathopod 2 to pereopod 5.
Variation. Antenna 1 as long as or slightly shorter than body; peduncle article 1 with 4 robust setae along ventral margin; accessory flagellum with 2–5 articles. Male gnathopod 2 palm with mid-medial tooth positioned proximally or distally, dactylus more falcate in larger specimens. Pereopod 7 merus more expanded in larger males.
Habitat. Intertidal to at least 11.5 m, possibly to 110 m, amongst algal fouling, primarily rhodophytes. Algal species from which M. petriei was collected are as follows:
Chlorophyta— Ulva sp.
Ochrophyta— Ecklonia radiata, Halopteris funicularis, Sargassum sinclairii.
Rhodophyta— Audouinella sp., Bostrychia harveyi, Brongniartella australis, Ceramium apiculatum, Ceramium vestitum, Corallina officinalis, Dasya sp., Delesseria sp., Erythroglossum sp., Griffithsia crassiuscula, Griffithsia sp., Haliptilon sp., Haraldiophyllum crispatum, Medeiothamnion lyallii, Phycodrys quercifolia, Plocamium microcladioides, Polysiphonia brodiei, Rhodymenia leptophylla.
Distribution. Wide ranging in New Zealand, from the Bay of Islands, Bluff and Milford Sound; possibly also from the vicinity of Three Kings Islands.
Remarks. Thomson (1882) established Moera petriei based on two syntype specimens taken by dredge at Port Pegasus, Stewart Island; both are now lost. In 1884, Chilton placed this species in the synonymy of Megamoera subcarinata Haswell (now Mallacoota subcarinata), where it remained until Lowry & Springthorpe (2005) redescribed the species based on syntypic material. Because of the morphological complexity of the genus Mallacoota and the confusion in the past over the identities of the New Zealand species, a neotype is designated here to fix the identity of Mallacoota petriei comb. nov. Unfortunately, no suitable specimens were available from the original type locality, Stewart Island. The only available Stewart Island Mallacoota specimens are of Chilton’s ‘form 2’, which correspond to the original concept of M. petriei, particularly in the distally pointed gnathopod 2 dactylus and strongly setose propodus and carpus. Although we could select a neotype from material of ‘form 2’ in order to preserve the original type locality, we favour preserving Thomson’s original concept of M. petriei. Thus, we select a neotype collected from Bluff, the nearest locality to Stewart Island from which we have suitable specimens of ‘form 1’.
Mallacoota petriei ranges widely in New Zealand spanning both main islands, in contrast to M. chiltoni which apparently does not occur north of the Subtropical Convergence. Thus, Chilton’s (1915: 326) report of Elasmopus subcarinatus from the tip of the North Island between “Three Kings and Cape Maria van Diemen” at 60 fathoms (110 m) is probably based on M. petriei.
Mallacoota petriei is most similar to species with a falcate male gnathopod 2 dactylus described from southeastern Australia. Mallacoota subcarinata is readily distinguished from M. petriei by the distinctly setose rather than glabrous dorsal pleon, and concave rather than rounded posterior margin of the pereopod 7 basis. Mallacoota euroka Lowry & Springthorpe, 2005, differs from M. petriei in only a few characters: the lack of a distinct distal robust seta on the peduncle article 1 of antenna 1; the more setose male gnathopod 2 propodus, and the different ornamentation of the male gnathopod 2 palm. Mallacoota kameruka Lowry & Springthorpe, 2005, has a rounded rather than slightly concave pereopod 5 and 6 basis and a much deeper sinus between the anterodistal shelf and the mid-palmar tooth. Mallacoota malua Lowry & Springthorpe, 2005, is also very similar, but lacks the notch on the posteroventral corner of coxae 1–3, and has a posterodistal ‘hood-like’ projection on the propodus of pereopods 6– 7. Mallacoota bulowara Hughes, 2011, also lacks the notch on coxae 1–3, and has a rounded posterior margin on the basis of pereopods 5–6. Finally, M. penelope Hughes, 2011, differs in the ornamentation of the male gnathopod 2 palm, lacks the posteroventral notch on coxae 1–3, and has a subquadrate posteroventral corner on the basis of pereopods 5 and 6.
Stebbing’s (1888) record of M. subcarinata from three Challenger stations, stn 168 off northeastern New Zealand [40°28’S, 177°43’E, 1100 fathoms (2013 m)], stn 161 off Melbourne [33 fathoms (60 m)], and an unnamed station off Port Jackson [30–35 fathoms (55–64 m)], with the corresponding plate 98 labelled as Elasmopus persetosus, was identified by Lowry & Springthorpe (2005) as their new species, Mallacoota kameruka Lowry & Springthorpe (2005). Mallacoota kameruka is known with certainty only from northeastern, southern and northwestern Australia in shallow inshore waters (shore to 28 m, Lowry & Springthorpe 2005; 55–64 m, Stebbing 1888), so the apparent 2300 m capture depth for the Challenger stn 168 specimen is suspect. The Challenger stn 168 specimen was probably mislabelled and may have originated in Australian waters.
description: Published as part of Kilgallen, Niamh M. & Ahyong, Shane T., 2011, The genus Mallacoota (Crustacea, Amphipoda, Maeridae) in New Zealand, pp. 22-36 in Zootaxa 2929 on pages 29-35, DOI: 10.5281/zenodo.202529