Thalestrella ornatissima Monard, 1935a

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), pp. 236-318 : 284-285

publication ID	https://doi.org/ 10.11646/zootaxa.5051.1.13
publication LSID	lsid:zoobank.org:pub:F94203E7-FCD1-4975-BAD3-0DF534806712
DOI	https://doi.org/10.5281/zenodo.5572452
persistent identifier	https://treatment.plazi.org/id/951887EA-FFF3-FFAF-FF51-D632E6D4FCCE
treatment provided by	Plazi
scientific name	Thalestrella ornatissima Monard, 1935a
status

Treatment

Parastenhelia anglica ( Norman & Scott, 1905) sensu Wells (1961)

Karllangia ornatissima ( Monard, 1935a) Gee (2006)

Original description. Monard (1935a): 45–46; Figs 87–96.

Additional descriptions. Wells (1961): 267–268; Fig. 2B View FIGURE 2 . Gee (2006): 2613–2621; Figs 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 .

Type locality. France, Brittany, Roscoff area; near Roc’h Iliévec ; dredged from sand .

Notes. Por (1964) recorded seven females (400 μm) of Parastenhelia ornatissima from detritus-laden littoral sand in Achziv, northern Israel (Levantine coast). He provided illustrations (Plate 11; figs 95–96) of the female P5 and the posterior half of the abdomen in dorsal aspect. Bodin (1968) reported both sexes in a midlittoral sand sample from Banc du Bûcheron (Ile de Ré) near La Rochelle, but gave no morphological details, while Soyer (1971) subsequently recorded it from Banyuls-sur-Mer. Gee (2006) recorded T. ornatissima comb. nov. as the most abundant species in the harpacticoid community at low tide level on St Martin’s Flat in the Isles of Scilly (only one specimen was found near the high-water mark, cf. Gee 2009). His detailed study of the previously undescribed male confirmed that this species has a sexually dimorphic antenna and belongs in the genus Karllangia (= Thalestrella ). Differences with Monard’s (1935a) description were dismissed as of no significance and attributed to the author’s imprecision in observing the minutiae of the mouthparts and, more importantly, the correct setation of the P4 exopod (two inner setae on exp-3 instead of three in the Scillonian material). Conversely, Por’s (1964) specimens, which allegedly share the same armature on P4 exp-3 as Monard’s material, were considered a potentially different species. In reality, Por did not illustrate leg 4 nor did he provide a setal formula, stating only that “Antennae, mouthparts and swimming legs are typical”. The only two discrepancies observed between Monard’s type material and the specimens from the Israeli coast are related to the anal operculum, which has fewer (7) and larger spinous projections, and the P5, which has slightly shorter setae (particularly on the endopodal lobe). These characters, together with the length:width ratio of the P5 exopod (shorter compared to the specimens from the Isles of Scilly), are known to show a certain level of variability and do not warrant the proposal of a new species for the Levantine material, at least not until it has been subjected to thorough re-examination. Gee (2006) showed that the specimens from the sand flats of Tresco and St. Martins (Isles of Scilly), previously identified by Wells (1961) as Parastenhelia anglica , are conspecific with T. ornatissima comb. nov. This claim was primarily based on the abundance and location data of the material, in conjunction with the description of the male P5 given in Wells (1961).

Thalestrella ornatissima comb. nov. shares the presence of the inner seta on P1 exp-2 with T. bengalensis comb. nov., T. psammophila comb. nov. and T. pulchra comb. nov. but differs from these species in the presence of only two outer spines on P3 exp-3.

The only other records of the type species are those by Willems et al. (2008) who obtained it from sandy shell gravel at 17–23m depth in the Koster-area, Swedish west coast, and by Alper & Sak (2018) who collected it in the mediolittoral zone of the Sarımsaklı coast (Balıkesir) in northwestern Turkey. A potentially morphologically close species was recorded under the name P. cf. ornatissima from the northern Gulf of Mexico ( Thistle 2003; Thistle et al. 1995a, 1995b; Suderman & Thistle 1998).