Linguimaera tias, Krapp-Schickel, 2003

Krapp-Schickel, T., 2003, Linguimaera Pirlot, 1936 (Crustacea, Amphipoda, Melitidae), a valid genus, Memoirs of Museum Victoria 60 (2), pp. 257-283 : 277

Linguimaera tias sp. nov.

Figures 13–15

Maera mastersi . — Barnard, 1972b: 108–10, figs 55–56.— Sheard, 1936: 177–178 fig. 3.— Sheard, 1937: 24.

Maera mastersii . — Hale, 1929: 215, fig. 213.— Chilton, 1916: 367.— Chilton, 1925: 317.— Hurley, 1954: 603.— Lowry and Fenwick, 1983: 236.

? Moera mastersi .— Chilton, 1911: 564.— Chilton, 1921: 72–73.

(not Megamoera mastersii Haswell, 1879b: 265 , pl. 1 fig. 1).

Material examined. Holotype. New Zealand, Otago Harbour, Shelly Beach , gravel pools, USNM 149478 (male 11.2 mm).

Paratype. Locality like above, USNM 149478 (ovigerous female 9.9 mm) .

Other material. Numerous specimens in 39 NMV collections from Vic. (Western Port, Port Phillip Bay, Portland Bay ), SA (Cape Northumberland), and eastern and central Bass Strait , 0–40 m depth, sedimentary and algal substrates .

Diagnosis. Gnathopod 1 propodus ratio length: breadth = 2.1–2.7, changing with age. Gnathopod 2 male, female propodus palm excavated, palmar corner in male without “thumb”- shaped prolongation; gnathopod 2 female similar in shape and not much different in size, slender. Pereopod 7 basis ratio length: breadth = 1.75. Telson with apical robust setae between half and total telson length.

Description. Adult male 10–17 mm, female 10–13 mm.

Eyes reniform, medially narrowed.

Antenna 1 0.8 of body length, peduncle article 1 shorter than article 2; flagellum of up to 46 articles, accessory flagellum of 6–7 articles. Antenna 2 gland cone nearly reaching end of article 3; peduncle reaches half of antenna 1 peduncle article 2; flagellum of 16–17 articles.

Mandible incisor and lacinia mobilis with strong blunt teeth, accessory robust setae serrate; molar huge and oblong; palp article 2: article 1 = 2.25, article 2: article 3 = 1.3, article 2 with 12–13 long setae in 4–5 groups; maxilla 1 inner plate width subequal to outer plate; outer plate with 7–8 simple to pectinate robust setae; maxilla 2 setae only distal, but many fine hairs also marginally.

Gnathopod 1 weakly sexually dimorphic. Coxa 1 anteriorly bluntly lengthened; basis ratio length: breadth = 2.5; merus posteroventally bluntly lengthened; carpus regularly rounded on posterior margin, length about twice to 2.3 width; propodus palm oblique, scarcely defined.

Gnathopod 2 weakly sexually dimorphic, different in size, not in shape, subchelate.

Female slightly dimorphic in size, similar in shape. Coxa 2 quadrangular, merus posterodistally with sharp tooth; propodus palm concave with blunt hump medially, defined by a posterodistal tooth, a straight part distally and shallow excavation proximally; 1 subdistal prominent robust seta on inner surface next to palmar corner, 6 smaller ones along the palm. Male dimorphic in size and shape, but in hyperadults both gnathopods again similar in size and shape; when dimorphic, one is as described for female, the other has a stronger defined palmar corner, distally followed by deeper semicircular excavation, while straight distal half of female has 1 or more blunt humps medially; dactylus stout, curved.

Pereopod 3 not much shorter than gnathopod 2 in male; pereopods 3, 4 basis and merus strong, other articles slim. Pereopods 5, 6 basis: propodus = 1.5; pereopod 7 male ratio length: width = 1.7.

Uropod 3 marginal setae on outer ramus in 4 or 5 groups.

Telson distomarginally with 2 small additional setae, no robust seta; in the excavation of lobes, 1 robust seta of about half telson length and another of one third telson length.

Etymology. Dedicated to our newest family member and sonin-law Matthias, shortened to Tias (noun in apposition).

Discussion. This species is very similar to Linguimaera mannarensis (Sivaprakasam, 1968) . Differences are: eyes oval, width medially narrowing (vs width not narrowing); lateral cephalic lobe anterodistal corner pointed and curved (vs very little developed, rounded); mandibular palp article 3 distally oblique (vs regularly rounded); gnathopod 1 propodus twice as long as wide (vs longer and narrower); gnathopod 2 carpus longer than wide (vs wider than long); pereopod 7 basis posterior margin only very weakly rounded (vs evenly excavate); telson subquadrate (vs longer than wide); marginally on first third no robust seta (vs. one stout robust seta).

Remarks. Thomson (1882: 235, fig. 4a) illustrated a New Zealand amphipod as Moera quadrimana with characters similar to the present species, although his fig. 4b probably deals with the true Quadrimaera quadrimana (Dana) .

Distribution. New Zealand: Otago Harbour, Shelly Beach ( Barnard, 1972b). Australia: Victoria: Port Phillip Bay, Western Port, Portland Bay, Cape Northumberland, Bass Strait. South Australia: Sellicks Beach ( Sheard, 1936). Gravel pools, sand, silty clay; 3.5–40 m depth.

Figures

Figure 13. Linguimaera tias sp. nov., male (Victoria, Port Phillip Bay). Hd scale x = 1 mm; mouthparts UL; Mx1, 2; Md; Mxp; LL in scale y = 1 mm.

Figure 14. Linguimaera tias sp. nov., male, female (Victoria, Port Phillip Bay). Gn1, 2 male 13 mm, Gn2 male 16 mm, Gn1, 2 female in scale x = 1 mm; Gn2´male 13 mm, Gn2´male 16 mm, Gn1´female, Gn2´female in scale y = 1 mm.

Figure 15. Linguimaera tias sp. nov., male, female (Victoria, Port Phillip Bay). P7´male‚ T in scale y = 1 mm; all other in scale x = 1 mm.