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Maera viridis Haswell

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Maera viridis Haswell

Moera viridis Haswell, 1880c:333–334, pl. 21: fig. 2.

Elasmopus viridis.—Stebbing 1906:445; 1910a:683.—?Chevreux 1908:482.

Maera viridis.—Chilton 1916: 362–365, figs. 3, 4; 1921a:73.

Maera inaequipes.—Hale 1929:214–215, fig. 212 [not Costa].

NOMENCLATURE.—This species bore the name “M. inaequipes (Costa)” for a period of time; Hale cited it as such; and J. L. Barnard (1962), in a key to Maera, grouped it and several other species under the name. J. L. Barnard (in press) discussed the species of Maera with a transverse palm on gnathopod 2 under the name “Maera incerta Chilton.” They are best known as the quadrimana complex after a typical species belonging to the group. There are about 10 different kinds of material from around the world in the literature belonging to this complex, and most of these have a name available. None of these species is the Mediterranean M. inaequipes, which has an oblique palm on gnathopod 2. Each has some small difference from another, in many cases the difference occurring on the male gnathopod 2. They may be races of a common stem, or they may be distinct species. I favor presently retaining a name for each, because Hawaii, for example, has two species of the complex, which indicates, by means of sympatric occurrence, that the various other elements of the complex, though allopatric, also may be good species rather than geographic races.

MORPHOLOGY.—In addition to the figures presenting the morphology of M. viridis, the following attributes are characteristic: the left mandible has 7 spines and the right has 6 in the spine row; the inner plate of maxilla 1 bears 2 large apical setae and 1–2 small subapical members in addition to the normal hairs on the medial margin; the inner plate of maxilla 2 has 1 or 2 slightly disjunct apicomedial setae; the lower lip has 5–6 tiny cones in tandem, forming a compact group on the apicomedial margin of each outer lobe; these are scarcely distinct from setae.

RELATIONSHIPS.—Maera incerta Chilton and M. viridis Haswell were maintained as distinct species by J. L. Barnard (in press). In the brief diagnoses of the species, he pointed out characters of the telson in M. incerta as unique to this group of Maera, but these same characters are found to be typical of M. viridis in contradistinction to the original description of the species. Maera incerta and M. viridis both have apically bifid lobes and 1 disjunct lateral spine. But comparison of New Zealand and Australian specimens, now possible, shows that the two species differ in other characters: M. incerta has only 1 accessory tooth on the tooth on the dactyls of the pereopods, whereas M. viridis has 3; the anteroventral cephalic tooth of M. incerta is much longer and thinner than that in M. viridis, and it is slightly twisted axially in contradistinction to M. viridis.

Maera viridis resembles Maera species from California (see J. L. Barnard, 1959, cited as M. inaequipes), but it differs in the absence of stout spines on article 2 of male gnathopod 2 (in M. viridis the margin bears weak setae), in the terminal development of an extra incision and the chelate projection of the palm on gnathopod 2, in the enlarged spines on article 1 of antenna 1, and in the form of the telson: the apices distinctly bifid, sparsely spined, and bearing a suggestion of a lateral acclivity containing an extra spine.

There may be a distinct species involved in Chilton’s (1916) record of M. viridis from Lord Howe Island, as male gnathopod 2 is very much like that of M. pacifica Schellenberg.

The amount of material available is insufficient to determine whether the full development of a malelike gnathopod 2 in an ovigerous female from Shepard 29 (South Australia, 6.9 mm long) is a consistent occurrence in this species or not. This in itself may be a good specific character, as other species of the complex have the female gnathopod 2 generally bearing a smooth palm.

MATERIAL.—Shepherd 8 (2), 13 (1), 29 (2), 30 (2), 31 (1), 49 (1), 52 (1), 54 (1); Slack-Smith 5 (1); JLB Australia 10 (5), 11 (1), 13 (9); Port Phillip 60 (?2).

DISTRIBUTION.—Warm-temperate Australia, littoral and sublittoral.

Melita Leach
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bibliographic citation
Barnard, J. L. and Drummond, M. M. 1978. "Gammaridean Amphipoda of Australia, Part III. The Phoxocephalidae." Smithsonian Contributions to Zoology. 1-551. https://doi.org/10.5479/si.00810282.103