Macandrewella Scott, 1909

Ohtsuka, Susumu, Nishida, Shuhei & Nakaguchi, Kazumitsu, 2002, Three new species of the genus Macandrewella (Copepoda: Calanoida: Scolecitrichidae) from the Paci ® c Ocean, with notes on distribution and feeding habits, Journal of Natural History 36 (5), pp. 531-564 : 532-534

Genus Macandrewella Scott, 1909

Diagnosis (emend.). Calanoida . Scolecitrichidae . Cephalosome fused to ®rst pediger. Rostrum bifurcate, bearing pair of long ®laments at tip. Single distinct cuticular lens present at base of rostrum. Anteromedial crest-like plate absent on cephalosome. Fourth and ®fth pedigers fused. Last prosomal somite carrying one or two pairs of acute or lobate processes in female, and pair of short, pointed prominences in male. Urosome four-segmented, at most one-third as long as prosome

. m 200 of isobaths: 200. stations sampling: Asterisks. stations sampling of Location

. 1. IG F in female, and ®ve-segmented in male, with anal somite almost telescoped into preceding somite. Caudal setae symmetrical or asymmetrical in female. Antennule composed of 23 free segments in female; male antennules asymmetrical, 18-segmente d on right side, 19-segmented on left side. Maxillary endopod bearing three wormlike and ®ve brush-like sensory setae. Mouthparts of male similar to those of female, but with some elements on mandibular palp slightly more reduced. Terminal elements of maxillipedal endopod more developed in male than in female. Strong processes present on posterior surface of endopods of legs 2 and 3 in both sexes. Female right/left leg 5 present or absent. Male leg 5 highly developed, both biramous; right exopod three-segmented, left two-segmented; endopods uni-segmented. Second exopodal segment of right leg forming distinct chela with third segment, bearing inner thumb-like process. Third exopodal segment of left leg armed with two membranous elements terminally.

Remarks. Scott (1909) established the genus Macandrewella accommodating M. joanae , and transferred Scolecithrix chelipes Giesbrecht, 1896 into this genus. The genus is clearly distinguishable from other scolecitrichid genera by the combination of the following characters: the presence of a single cephalic lens; the highly developed male leg 5 with the second and third exopodal segments of the right leg forming a chela.

Later, Farran (1936) created a closely related genus Scolecocalanus with a single cephalic lens at the rostral base. Main diOEerences between Macandrewella and Scolecocalanus are as follows (see Campaner, 1989): an anterior crest-like cephalic expansion present in Scolecocalanus and absent in Macandrewella ; the female ®fth legs are two-segmented with a common base or absent in Macandrewella , whereas in Scolecocalanus , the left leg is uni-segmented with a stout terminal spine and the right leg is reduced. In addition, the rostral ®laments are long and slender in Macandrewella but short and thick in Scolecocalanus . The only known male of Scolecocalanus is S. spinifer Wilson, 1950 , in which the two-segmented exopod of the right leg 5 does not form a chela.

The asymmetry of the male antennules of Macandrewella was ®rst mentioned by Gopalakrishna n (1973), which is con®rmed in the three new species described herein.

Type species. Macandrewella joanae Scott, 1909 (monotypy).