Sunamphitoe aorangi ( J.L. Barnard, 1972 )

Peart, Rachael A., 2017, Analysis of the genus Sunamphitoe Spence Bate, 1857 (Amphipoda: Ampithoidae) with descriptions of eight new species, Zootaxa 4269 (3), pp. 301-345 : 308-310

Sunamphitoe aorangi ( J.L. Barnard, 1972)

Ampithoe aorangi J.L. Barnard, 1972: 27 , 37, figs 8, 9 (part, not 10a–e = S. mixtura sp. nov.). Peramphithoe aorangi .— Shin, Coleman, Hong & Kim, 2015: 261 –264.

Not Peramphithoe aorangi .— Hughes & Peart, 2014: 93 –95, fig. 61. (= S. lehae sp. nov.)

Material examined. Holotype: male, 5.3 mm, NIWA 798 , intertidal wash of algae and their rhizomes, Eve Bay, off Strathmore Park, Wellington, New Zealand, 41 ° 19.8’S 174 ° 49.8’E, NZOI Sta E 966, coll. J.L. Barnard, 5 November 1968 .

Diagnosis. Antenna 2 slender, similar in size to antenna 1. Mandible palp with 3 articles. Maxilla 1 inner plate with one slender seta. Maxilla 2 inner plate narrower than outer. Gnathopod 2 carpus shorter than propodus; propodus broad; palm transverse, entire, no midmedial tooth, no defining posterodistal tooth, with defining robust seta; dactylus overreaching palm, inner margin smooth with small setae. Pereopod 5 distal articles slightly broadened. Pereopods 6–7 distal articles slender. Uropod 3 peduncle with distal robust setae absent; outer ramus with patch of lateral denticles, lateral setal fringe consisting of only one seta; inner ramus with one distal robust seta. Telson distally subacute, apical cusps small, apical and lateral setae and no lateral denticles.

Description. (Based on holotype male, 5.3 mm, NIWA 798. Female not known.)

Head slightly longer than deep. Antenna 2 peduncular article 4 subequal in length to article 5. Mandible molar well developed, triturating, with seven robust setae in the accessory setal row; palp article 1 shorter than article 2 (0.5 ×), article 2 longer than article 3 (1.5 ×) article 3 longer than article 1 (1.3 ×). Lower lip outer plate mandibular lobes with curved margins, subacute apically. Maxilla 1 palp well developed, with apical robust setae. Maxilliped outer plate narrow, reaching midlength of palp article 3; palp article 4 covered in small setules.

Pereon. Gnathopod 1 smaller than gnathopod 2, without densely setose margins, coxa subequal to gnathopod 2 coxa, with sparse ventral setal fringe; not produced anteroventrally; anterior margin straight, distoventral corner with small produced rounded corner/tooth; basis longer than coxa, with medial and lateral simple setae, anteroventral lobe reduced/vestigial and without setae; merus produced to form small subacute lobe, anterior margin with setae absent; carpus longer than merus, subtriangular, shorter than propodus (0.7 ×), posterior margin slightly lobate, rounded, with slender setae on posterior margin, anterior margin with distal slender setae only; propodus narrow (length 2.1 × width), subrectangular; palm transverse, entire, without posterodistal tooth defining palm, with one defining robust seta; dactylus overreaching palm, inner margin serrated. Gnathopod 2 without densely setose margins; coxa ventral margin with row of setules and tuft of slender setae on posterior corner; basis longer than coxa with sparse slender lateral setae, anteroventral lobe reduced/absent and without setae; merus produced to form small subacute lobe, anterior margin without setae; carpus longer than merus, subtriangular, anterior margin with slender setae distally; propodus not produced into anterodistally setose lobe; dactylus tapering evenly, acute, inner margin smooth. Pereopods 3–4 basis and merus expanded. Pereopods 5–7 weakly prehensile, propodus slightly expanded distally, with two distal robust setae; dactylus hooked.

Pleon. Epimeron 3 posteroventral corner broadly rounded. Uropod 1 peduncle with six marginal robust setae, and lateral setal fringe absent; inner ramus slightly longer and narrower than outer ramus, with two marginal robust seta and four apical setae; outer ramus with three marginal and four apical robust setae. Uropod 2 peduncle with three marginal robust setae and no lateral slender setal fringe; inner ramus slightly longer and narrower than outer ramus and with three marginal and four apical robust setae; outer ramus with four marginal and four apical robust setae. Uropod 3 peduncle longer than broad (2.3 ×), peduncle long with respect to rami (2.7 ×), marginal robust setae absent, with two marginal slender setae present; rami broad; outer ramus subequal to inner ramus.

Remarks. Considerable confusion has surrounded the identity and distribution of S. aorangi , owing primarily to the original species description ( Barnard 1972). Barnard (1972) described two forms of gnathopod 2 and variations in other parts of the animal, implying (though not explicitly) that these were size-related. There are numerous other differences, however, that cannot be attributed to mere growth differences. Barnard (1972) designated a small specimen as the holotype, one without the distinctive second gnathopod. Hughes & Peart (2014) reported S. aorangi from Australia, and for the first time outside of New Zealand waters. The Australian form, however, shows substantial differences from New Zealand S. aorangi and is therefore described as a separate species ( S. lehae sp. nov.). Shin et al. (2015) noted that the holotype was significantly different from the other specimens figured by Barnard (1972), and there was no evidence that all represented the same species. Examination of the original material reported by Barnard (1972) revealed that the apparently more mature specimen differs considerably from the holotype in features other than just the gnathopods ( Table 1). The holotype is well figured, but apart from the aforementioned larger specimen of Barnard, other material he reported is no longer extant. The other confusion that has arisen from Barnard’s (1972) account is inconsistency between the statement that females of S. aorangi were not known, and inclusion of diagnostic features and figures of females. Reexamination of the extant material indicates that the female can be aligned with the second form herein referred to a new species ( S. mixtura sp. nov.) ( Table 1).

The phylogenetic analysis shows that throughout the genus there are groups of species united by the differing general morphology of the second gnathopod ( Fig. 1 ). Although Sunamphitoe mixtur a sp. nov., S. lehae sp. nov., S. tjibaoui and S. jonathani sp. nov. share similar morphology of gnathopod 2, they are dispersed throughout the tree, with S. lehae and S. jonathani being most closely related. The differences between S. aorangi ( J.L. Barnard, 1972) , S. mixtura and S. lehae are outlined in Table 1.

Distribution. Wellington, New Zealand.

Figures

FIGURE 1. One of fifteen most parsimonious trees (length 335 steps, consistency index 0.248, retention index 0.440). Clade numbers correspond to character state reconstructions listed in Appendix C. (p) indicates former placement in Peramphithoe. * indicates species described in this paper.