Quadrimaera pacifica ( Schellenberg, 1938 )

Krapp-Schickel, Traudl, 2009, Maeridae, the Ceradocus group *, Zootaxa 2260 (1), pp. 598-642 : 627-629

Quadrimaera pacifica ( Schellenberg, 1938)

( Fig. 20 )

Maera pacifica Schellenberg, 1938: 42 , figs 19–20. — Nayar, 1959: 23, pl. 8, figs 16–17. —J.L. Barnard, 1965: 511. —

J.L. Barnard, 1970: 150, figs 92–93. —J.L. Barnard, 1971: 84, figs 38–41. — Ledoyer, 1972: 227, fig. 43 (forme A).

— Ledoyer, 1983: 534, figs 201–202 (forme A). — Kim & Kim, 1987: 11, fig. 10. — Ruffo, Krapp & Gable, 2000:

13. Maera kaiulani J.L. Barnard, 1970: 141 , figs 90–91. —J.L. Barnard, 1971: 84, figs 38–41. Quadrimaera kaiulani . — Krapp-Schickel & Ruffo, 2000: 194. Quadrimaera cf. pacifica . — Appadoo et al., 2002: 650, fig. 5.

Material examined. 12 adults and juveniles (1 male 5 mm, 2 slides, 1 female, 1 slide), AM P77721( SEL /LZI- 2-3) ; 20 adults and juveniles, (1 male, 5 mm, 2 slides) AM P77722 ( SEL /LZI-2-4); 1 young female, AM P77723 ( SEL /LZI-2-6) .

Type locality. Makin, Kiribati (~ 1°40'S 179°22'W) .

Description. Based on male, 5.0 mm, AM P77721.

Head. Head, lateral cephalic lobe rounded, anteroventral slit absent, anteroventral corner acutely lengthened. Antenna 1 peduncular article 2 longer than article 1, accessory flagellum with 3–4 articles. Antenna 2 lacking gland cone, article 4 longer than article 5. Upper lip lobate and thickened. Mandible palp article 1 distally somewhat oblique, resulting in knee-like articulation, lacking distal prolongation, article 3 clearly longer than article 2.

Pereon. Gnathopod 1 coxa subquadrate, without acute anterodistal prolongation; carpus with shallow notch on anterodistal margin; propodus with rounded posterior margin. Gnathopod 2 male propodus subrectangular, widening distally, palmar margin with small medial U-shaped shallow excavation and with deeper and narrower excavation next to prominent, acute defining spine; dactylus with 1 seta on outer margin, inner margin slightly bulging. Pereopods 3–7 anterior margins of all articles and posterior margin of the merus with many groups of short robust setae, posterodistal corners of carpus, merus and propodus with a bundle of many robust setae, those on the merus of pereopod 7 surpassing the middle of the carpus, propodus hind margin smooth or with 1–2 setae, dactylus bifid.

Pleon. Epimera 1–3 smooth, posterodistal corner blunt. Uropod 3 rami peduncle and outer ramus of about the same length, the inner ramus a little shorter; both rami distally truncate, with about 5 robust setae which are shorter than the rami. Telson deeply cleft, lobes obliquely truncate, distally with 3–5 long robust setae.

Female (sexually dimorphic characters). Gnathopod 2 palm rounded and smooth, with a V-shaped incision, or medially a small excavation, next to the defining spine.

Variation. Uropod 3 rami morphologically extremely different according to the age: Juveniles have the rami much narrower, and the outer one 1.5 x longer than the peduncle (J.L. Barnard, 1970: 151 fig. 92) and the inner ramus is much shorter than the outer one. Telson in juveniles not truncate, but distally with shallow excavation, distal corners lengthened to acute tips.

Habitat. Protected beach, coral rubble, sand, algae, wood pieces, 0–0.3 m.

Remarks. As already mentioned in Ruffo, Krapp & Gable (2000), the triangular spine on the inner margin of the dactylus of gnathopod 2 (drawn by Schellenberg 1938: fig. 19) was never found until now, although a hyperadult male of 7 mm of the syntypical series could be checked.

Ruffo, Krapp & Gable (2000) required more material of different ages to understand better the often cited "variability" of this species. In the current collection this was the case, and there were specimens of different sizes and morphs together in one sample. It was found that, similar to what is already known for Quadrimaera serrata (see J.L. Barnard 1970: fig. 97), the uropods and telson change their shape during morphological development. The uropod 3 rami of juveniles are very different in length to those of adults, such as shown for Maera kaiulani (see J.L. Barnard 1970: 147, figs 90, 91—never again reported). Thus there is strong evidence to suggest that Q. kaiulani (J.L. Barnard, 1970) is a juvenile stage of Quadrimaera pacifica . The fact that juveniles start with such a short ramus in uropod 3 indicates that Quadrimaera pacifica , which is placed in the same group as Q. quadrimana ( Dana, 1853) , Q. reishi (J.L. Barnard, 1979) , Q. schellenbergi ( Ruffo, 1938) , Q. cristianae Krapp-Schickel & Ruffo, 2000 , and Q. ceres ( Ruffo, Krapp & Gable, 2000) , where such development is not reported, may not share the same origin as other members of this genus.

Myers (1985: 112, figs 89, 90) illustrated material under the name of Maera pacifica which could well be a hybrid of Q. quadrimana and Q. pacifica , as it has a much deeper medial incision on gnathopod 2 palm than usual for Q. pacifica , but lacks the second V-shaped incision typical for Q. quadrimana . The identical shape is given in Ledoyer (1972: 230, pl. 44) as Maera pacifica forme B and in Griffiths (1976: 25, fig. 8) again under Maera pacifica . It is tempting to define it as a separate species, but morphologically there is no other reliable character for distinguishing.

Distribution. Australia. Queensland: Lizard Island (current study). Fiji ( Schellenberg 1938, Myers 1985). Hawaii ( Schellenberg 1938, J.L. Barnard 1970). Kiribati ( Schellenberg 1938). Madagascar ( Ledoyer 1972). Mauritius ( Appadoo et al. 2002).

Figures

FIGURE 20. Quadrimaera pacifica (Schellenberg, 1938), male, 5.0 mm, ovigerous female, juvenile, AM P77721, Palfrey Island, Lizard Island, Great Barrier Reef.