Chalarostylis Norman 1879

Chalarostylis Norman, 1879

Chalarostylis Norman, 1879: 65.

Dasylamprops Reyss, 1978b: 82.

Type species. Chalarostylis elegans Norman, 1879, by monotypy.

Diagnosis. Carapace not dorsoventrally flattened, marginal carina absent, eyelobe present, pseudorostral lobes short, blunt. Antennule flagella unequal, accessory flagellum shorter than main flagellum. Mandible navicular. Maxillule palp with 2 setae. Pereopod 1 robust, with group of long, stout setae on dactylus. Pereopod 5 longer than basis of pereopod 4. Telson short, less than 0.7 length of peduncles. Uropod endopod of 3 articles. Uropod exopod article 1 at least 0.5 length of article 2. Female with fully developed exopod on pereopod 2, rudimentary exopods on pereopods 3–4, without pleopods. Male with short antenna, not extending past pereon, with or without penial lobes, with 3 pairs of pleopods.

Species. C. brenkei (Mühlenhardt-Siegel, 2005), C. bruunae n. sp., C. canadensis (Vassilenko, 1988) C. elegans Norman, 1879, C. guanchi (Reyss, 1978b), C. longisetae (Corbera, 2006).

Remarks. Chalarostylis is a deep sea genus, and the first pereopod is frequently broken off at the basis/ ischium joint. Specimens with the first pereopod broken may easily be confused with Hemilamprops, as also observed by Alberico et al. (2014). With the exception of C. canadensis, the accessory flagellum is much shorter than the main flagellum, which serves to differentiate this genus from Hemilamprops. It is possible that the incomplete specimens described as Hemilamprops sp. in Day (1978) represent another species of Chalarostylis, as the anterior margin of the carapace and the dorsal crest are spined, and the telson is less than 0.5 the length of the uropod peduncles.

The diagnoses of Dasylamprops and Chalarostylis shared the short telson and the accessory flagellum of the antennule much shorter than the main flagellum, unusual characteristics within the Lampropidae. The Dasylamprops diagnosis. also included a robust pereopod 1 with a group of stout setae on the dactylus, apparently differentiating it from Chalarostylis. However, the holotype material of Chalarostylis elegans has the first pereopods missing all articles distal of the basis, and none of the subsequently published records of Chalarostylis before 2007 included any additional description, suggesting the pereopod 1 was broken on all specimens, as is frequently encountered in cumaceans with long first pereopods, including many Hemilamprops, diastylids and gynodiastylids. Gerken & McCarthy (2007) redescribed both the holotype and an additional entire specimen of Chalarostylis elegans, which included a complete, robust pereropod 1 with a group of stout setae on the dactylus. With a complete overlap of the generic diagnoses (short telson, short accessory flagellum, robust pereopod 1), it became clear that Chalarostlyis and Dasylamprops were synonymous, and Dasylamprops was the junior synonym (Gerken & McCarthy 2007).

Alberico et al. (2014) suggested that the steep angle of the articulation between the merus and carpus of maxilliped 1 be added to the generic diagnosis. However, there is much variation across the Lampropidae in this angle within genera (where it has been observed), therefore it does not seem at present to be of generic value.