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Specific Diagnosis.
Dorsal surface of body smooth. First side plate with front corner produced, acute. Third pleon segment with posterior margin smooth, inferior margin smooth or obscurely serrate posteriorly, angle acute, slightly produced. Eyes round. First antennae with flagellum about the same length as peduncle, accessory flagellum about half as long. Second antennae with flagellum subequal to ultimate joint of peduncle. First gnathopod with depression in anterior border of carpus, inner surface of carpus with numerous oblique rows of setae arranged as in Fig. 5, gn1.
Second gnathopod large in both sexes, palm somewhat oblique, defined by an acute tooth, convex and serrulate or irregularly toothed in the female, more toothed and usually with a deep central notch in the male. Third uropod with rami subequal, considerably longer than the first and second. Telson deeply cleft, each lobe bidentate, the inner tooth being longer than the outer.
Of this species I have specimens from the following New Zealand localities: Paterson Inlet, Stewart Island (these are some of the specimens referred to M. quadrimana by G. M. Thomson in 1882); Chatham Islands, Miss S. D. Shand.
Distribution.—The species has long been known under various names from the North Atlantic and the Mediterranean, and has been recorded from the Indian Ocean by Walker, and more recently from Australia by Stebbing.
I feel fairly confident that the New Zealand specimens rightly belong to this widespread species. It appears to be very closely allied to M. viridis Haswell, and, as in that species, it has the characteristic depression
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on the anterior margin of the carpus of the first gnathopod. The two species were united by Della Valle, and in each there appear to be so many varieties that it may be difficult to draw a distinction between them in all cases. The more typical examples of M. inaequipes, however, appear
Fig. 5.—Maera inaequipes, female—a specimen from Chatham Islands gn1, first gnathopod (inner surface); gn2, second gnathopod (inner surface).
to be distinguished by the more oblique palm of the second gnathopod, and by having the third uropods considerably longer than the preceding pairs. Stebbing (1906, p. 436, and 1910A, p. 599) describes the palm of the second gnathopod as “almost transverse,” and this usually appears to
Fig. 6.—Maera inaequipes, female—a specimen from Chatham Islands. pl. and urp, terminal portion of body.
be so in the males, but in the female it is distinctly oblique, though not greatly so, and apparently this is also the case with some forms of the male, as, e.g., in M. hirondellei Chevreux. The third uropods, again, appear fairly long. Stebbing describes the rami as “not very long,” but they
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seem always to reach well beyond those of the preceding pairs, and they are considerably elongated in some of the New Zealand specimens; in one of the specimens from the Chatham Islands they are much shorter on both sides, hardly reaching beyond the second and third, but I think this condition is abnormal, and due to the regeneration of appendages that had previously been lost. Walker has pointed out that the fourth and fifth peraeopoda are more massive and spinous in the Ceylon than in the Mediterranean specimens, and has also drawn attention to the fact that the species forms a connecting-link between the genera Maera and Elasmopus, mentioning among the characters that resemble the latter genus the comparatively short rami of the third uropods. In the New Zealand specimens, however, they are quite long enough to justify the inclusion of the species in Maera, and the species appears to differ also from Elasmopus in having the second gnathopods of approximately the same size in both sexes, and in having the setae on the inner surface of the carpus of the first gnathopod arranged on a different pattern.
Maera hirondellei Chevreux differs from the more typical forms in having the accessory appendage shorter, and in the oblique palm of the second gnathopod of the male; but these differences are perhaps only of varietal importance. The general resemblance in other characters is very close.
Miers mentions (1884, p. 569) that in the British Museum there is a specimen from the Korean Seas which cannot, he thinks, be distinguished from M. truncatipes (Spmola)—i.e., from M. inaequipes (A. Costa). M. diversimana Miers appears also to be closely allied to the present species and to M. viridis Haswell, but apparently differs in having the segments of the pleon dorsally toothed, and in having the right and left second gnathopods unequal in size, while in M. inaequipes they are, according to Stebbing, as a rule, “quite alike in size and sculpture.” The name of the species, however, indicates that this is not always so, and probably in this as in other species with large gnathopods the appendage on one side may differ from that on the other in some in dividuals, while in others they are alike.