Microthalestris polaris
- Dataset
- Johnwellsia, a new intertidal genus of Parastenheliidae (Copepoda, Harpacticoida) from the Taiwan Strait, China, including a review of the family and key to genera
- Rank
- SPECIES
- Published in
- Huys, Rony, Mu, Fanghong (2021): Johnwellsia, a new intertidal genus of Parastenheliidae (Copepoda, Harpacticoida) from the Taiwan Strait, China, including a review of the family and key to genera. Zootaxa 5051 (1): 236-318, DOI: 10.11646/zootaxa.5051.1.13, URL: https://doi.org/10.11646/zootaxa.5051.1.13
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Hexanauplia
- order
- Harpacticoida
- family
- Miraciidae
- genus
- Microthalestris
- species
- Microthalestris polaris
description
Additional descriptions. Chislenko (1967: 140 – 144, Figs 45 – 46); Chislenko (1977: 246, Fig. 6 – 1, 2).
diagnosis
Differential diagnosis. Microthalestris. Body length 550 – 800 μm in ♀, 400 – 420 μm in ♂. Antenna with 2 - segmented exopod bearing two setae on exp- 1 and two lateral and three apical elements on exp- 2; armature of endopod unconfirmed but likely without penicillate spines. P 1 exopod about 75 % length of endopod; exp- 2 elongate, about 2.5 times as long as exp- 1, and about 55 % length of enp- 1; insertion point of inner seta of enp- 1 at 25 % of inner margin length; exp- 3 with two unipinnate spines and two geniculate setae; enp- 2 with one minute seta and two non-geniculate claws. Armature pattern of ♀ P 2 – P 4: P 3 endopod ♂ 3 - segmented, with apophysis on enp- 3, armature pattern [1.1.02 + apo]. P 5 ♀ with elongate exopod (about 2.4 times as long as maximum width), inner margin and proximal half of outer margin straight, with eight elements, proximal outer one long, outer apical one short; endopodal lobe with five elements, innermost one well developed. P 5 ♂ exopod 3 - segmented, with seven elements, outer seta of exp- 1 very long, longer than or as long as outer basal seta; endopodal lobe with two elements. Armature of P 6 ♂ unconfirmed. Caudal ramus seta V with slightly swollen proximal part.
etymology
Etymology. The species name is derived from the Latin polaris, meaning polar, and refers to the Arctic distribution of this species. Notes. The species appears so far to be restricted to the Arctic Ocean and its marginal waterbodies such as the White Sea. It has been recorded from Kandalaksha Bay (Chislenko 1967), Svalbard (Mielke 1974) and Franz Josef Land (Chislenko 1977). Kornev & Chertoprud (2008: 196 – 197, Fig. 5.94 – A, Б, B) also reported P. spinosa from the White Sea, including an aberrant specimen, and reproduced Chislenko’s (1967) illustrations of the P 1 and P 5 of both sexes. They mentioned substantial variation in female body length (550 – 800 μm) but this is a verbatim account of Chislenko’s (1967) measurements. It is also not clear whether the variability included in their armature formulae of P 3 – P 4 (number of inner setae on P 3 – P 4 exp- 3 and P 4 enp- 3; Table 1) is based on their own obervations of White Sea material or reflects variability reported in the literature. Since the authors provided no direct evidence that they were dealing with M. polaris sp. nov., their record is at present to be considered as unconfirmed. This uncertainty is exacerbated by the fact that, despite the reported variability on other segments, the White Sea specimens appear to be consistent in the lack of the inner seta on P 3 exp- 1 (which is present in M. polaris sp. nov.). Chislenko (1967) collected two females from washings of the demosponge, Semisuberites cribrosa (Esperiopsidae), in Franz Josef Land but this association is to be regarded as accidental (Huys 2016). Previous records of Thalestris forficula from Arctic localities may refer to M. polaris sp. nov. but in the absence of morphological or other compelling evidence they must remain unconfirmed. These include the records from Lille- Karajak fjord in western Greenland (Vanhöffen 1897), Cape Gertrude in Franz Josef Land (Scott 1899), between Kolguev and Novaya Zemlya (Scott & Scott 1901 – as T. forficulus), Bear Island (Bjørnøya) and Hope Island, Svalbard (Scott & Scott 1901 – as T. forficulus), the Arctic islands north of Grinnell Land, Canada (Sars 1909) and Seydisford in Iceland (Jespersen 1940; Klie 1941 – both as Parastenhelia forficula). Similarly, the Arctic records of Parastenhelia spinosa from Iceland (Ólafsson et al. 2001; Steinarsdóttir et al. 2003; Steinarsdóttir & Ingólfsson 2004), Kandalaksha Bay in the White Sea (Brotskaya 1962; Chertoprud et al. 2005) and from mesozooplankton in the Barents Sea (Dvoretsky & Dvoretsky 2010) require authentication before they can be considered conspecific with M. polaris sp. nov.
materials_examined
Type material. The female specimen illustrated by Mielke (1974: Abb. 9 A – B) is here designated as the holotype of M. polaris sp. nov. (ICZN Arts 16.4 and 72.5.6). The species can be differentiated by the characters listed in the diagnosis below and those mentioned and illustrated in Mielke (1974) (ICZN Art. 13.1). Type locality. Svalbard archipelago, Spitsbergen, Longyearbyen; littoral zone.