Dahms H.-U.1, Schizas N.V.2, Shirley Th.C.3 2005. Naupliar evolutionary novelties of Stenhelia peniculata (Copepoda, Harpacticoida) from Alaska affirming taxa belonging to different categorial rank // Invertebrate Zoology. Vol.2. No.1: 1–14 [in English].

1 Hong Kong University of Science and Technology (HKUST), Department of Biology, Coastal Marine Lab (CML), Clear Water Bay, Hong Kong, SAR – China. E-mail: hansd@ust.hk

2 Department of Marine Sciences, University of Puerto Rico, Mayagüez Campus Isla Magueyes Laboratories, P.O. Box 908, Lajas, PR 00667, Puerto Rico e-mail: n_schizas@cima.uprm.edu

3 Juneau Center, School of Fisheries & Ocean Sciences, University of Alaska Fairbanks, 11120 Glacier Hwy, Juneau, AK 99801, U.S.A. e-mail: Tom.Shirley@uaf.edu

doi: 10.15298/invertzool.02.1.01

ABSTRACT: All six naupliar stages of Stenhelia peniculata (Lang, 1965) from Auke Bay near Juneau (Alaska) are described. Naupliar morphology within the Stenheliinae differs among species and even more at supraspecific level. Nauplii of S. peniculata are characterized by the following apomorphies compared to the only other species of Stenhelia where nauplii have been studied, namely S. palustris (cf. Dahms, Bresciani, 1993): third antennal segment bears three (S. peniculata) or two (S. palustris) medial setae at the third naupliar stage; mandibular endopod with three or four setae on outer lateral field at the sixth naupliar stage; no spinulation on mandibular exopod or strong spinulation; first maxilla with three or two setae. The nauplii of both these stenheliid species differ from those of Pseudostenhelia wellsi Coull, Fleeger, 1977 by the terminal seta of the first antenna, which is as long as the third segment (Stenhelia) or three times as long as the third segment (Pseudostenhelia); the four middle setae of the antennal endopod are of regular size (Stenhelia), instead of two of the four being much longer; the proximal seta of the mandibular exopod long instead of being short (Pseudostenhelia); their endopod having an outer lateral field with one long seta (Stenhelia) instead of having three long setae. A reaffirmation of the Stenheliinae Brady, 1880 is supported by the following stenheliinid apomorphies in the morphology of the nauplii (as evidenced from a comparison of Stenhelia and Pseudostenhelia, with all other oligoarthran harpacticoid nauplii as an outgroup): lateral edge of the naupliar shield bears protuberances on either side (Stenheliinae) instead of no protuberance (Oligoarthra); masticatory process of the second antenna is peculiarly fan-shaped distally (Stenheliinae) instead of tapering terminally (Oligoarthra); antennal exopod strongly developed, three-segmented and upwardly curved (Stenheliinae) instead of being four-segmented and never strongly developed (Oligoarthra); the whole mandible is of peculiar shape and orientation (Stenheliinae) instead of being common (Oligoarthra); the posterolateral field of the mandibular endopod bears a remarkable strong, inner spinulose spine (Stenheliinae) instead of lacking such spine (Oligoarthra); the three distal exopodal setae are of unique structure (Stenheliinae).

KEY WORDS: postembryonic development, morphology, key to stages, phylogeny.

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