Originally described from Greenland, Juxtacribrilina annulata (Fabricius, 1780) (previously known as Cribrilina annulata) has long been regarded as having a circumpolar, Arctic-boreal distribution. The genus Juxtacribrilina (Yang, Seo, Min, Grischenko & Gordon, 2018) was established to accommodate J. annulata and three related North Pacific species formerly in Cribrilina Gray, 1848 that lack avicularia, have a reduced (hood-like, cap-like, or vestigial) ooecium closely associated with modified latero-oral spines to form an ooecial complex, and produce frontally or marginally positioned dwarf ovicellate zooids. While two recently described NW Pacific Juxtacribrilina species having a vestigial ooecium clearly differed from J. annulata, other Pacific records for the latter remained questionable, as the differences between J. annulata and Pacific populations were unclear. Here we provide descriptions for five species from the North Pacific and Sea of Okhotsk. We identified a specimen from the Sea of Okhotsk as J. annulata (Fabricius). Among the other four species, J. ezoensis n. sp. has a trans-Pacific distribution (abundant at Akkeshi, Hokkaido, Japan; also detected in the Commander Islands and at Ketchikan, Southeast Alaska); J. pushkini n. sp. was found only at Ketchikan; J. dobrovolskii n. sp. was found only in the Kurile Islands; and J. tumida n. sp. was found only at Kodiak, Gulf of Alaska. These four species all differ from J. annulata in having one or two frontal pore chambers on the proximal gymnocyst of most zooids; in budding dwarf ovicellate zooids from these frontal chambers rather than from basal pore chambers; in producing dwarf zooids more abundantly; and in having ooecia that are somewhat to markedly more reduced (cap-like or vestigial) and more closely integrated with the modified latero-oral spines. Furthermore, in the Pacific species, the kenozooidal ooecium in basal zooids arises from the roof of distal pore chamber of the maternal zooid; ovicellate zooids can thus bud a distal autozooid and are often arranged in columnar series with other zooids. In J. annulata, the hood-like kenozooidal ooecium is budded from the maternal zooid in place of a distal zooid; ovicellate zooids do not bud a distal autozooid and are usually not arranged in columnar series.
|Состояние||Отправлено - 2021|
Предметные области Scopus
- Земледелие и биологические науки (все)