Coscinasterias tenuispina

Coscinasterias tenuispina (Lamarck, 1816)

Asterias tenuispina Lamarck, 1816: 561–562.

Coscinasterias tenuispina — Clark & Downey 1992: 427–428, figs. 63h, i, pl. 101, figs. A, B; Alves et al. 2002; Pérez-Ruzafa et al. 2002: 280–281; Netto 2006: 34, fig. 16c, pl. 5b; Koukouras et al. 2007: 70; Ventura et al. 2007: 228; Ventura et al. 2008c: 172; Micael & Costa 2010: 321; Micael et al. 2012: 2–4; Gondim et al. 2014: 43–44, fig. 9i–m; Fonseca 2015; Madeira et al. 2019: 64–66, fig. 12.

Distribution. France, Italy, Croatia, Spain, Portugal, Azores, Madeira, Turkey, Greece, Malta, Canary Islands, Bermuda, Cape Hatteras, Cape Verde, North Carolina, Cuba, Gulf of Mexico, Guyana, Ascension Island, Saint Helena (Koukouras et al. 2007; Madeira et al. 2019; GBIF, 2020). BRAZIL: Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Santa Catarina (Rathbun 1879; Verrill 1915; Brito 1962; Tommasi 1970; Clark & & Downey 1992; Ventura et al. 2007; Gondim et al. 2014; Fonseca 2015). Depth. 0–165 m (Clark & Downey, 1992).

Biological notes. Coscinasterias tenuispina inhabits rocks, biogenic detritus, sandy and silty sand bottoms, and meadows of seagrass (Koukouras et al. 2007), and typically feeds on mussels and other epifaunal organisms (Ventura et al. 2007). Adults and juveniles are believed to inhabit different depths (Tortonese 1965). This species can reproduce asexually by fission (Alves et al. 2002), and Fonseca (2015) has shown that the contribution of sexual reproduction to maintain four populations in Rio de Janeiro is very low compared to that of asexual reproduction, contrary to the findings by Pazotto (2010) in the same populations.

This species is classified as “Vulnerable” (baseline data indicates that the population size has been reduced by at least 30%) by the Ministry of the Environment (MMA 2018).

Holotype. The type specimen, most likely deposited at the Muséum National d’Histoire Naturelle, Paris, is currently lost (Marc Eléaume and Christopher Mah, pers. comm. on 30 Sep 20).

Type locality. European Ocean (Lamarck, 1816; Clark & Downey, 1992), possibly the Mediterranean Sea.

Remarks. Although C. tenuispina has been recorded for Bahia, few specimens have been collected and as Gondim et al. (2014), we could not examine any. We did not have access to the specimens at the EQMN and the single-armed specimen recorded by Rathbun (1879), deposited at the YPM (YPM IZ 1582.EC), is apparently missing. The last reference that we have for this specimen is that it was examined by Addison Emery Verrill, together with three other specimens from the North Atlantic (YPM IZ 1453.EC and YPM IZ 1584.EC); the label from YPM 1582.EC was found in a jar with a single specimen tagged with the label YPM IZ 1453.EC (Daniel Drew and Eric Lazo-Wasem, pers. comm. on 15 Jul 20).

Downey (1973) considered the specimen (R 30 mm) she examined from Florida as a juvenile based on morphological differences from larger specimens, for example, the presence of only a few dorsolateral plates (vs. one or two regular rows of dorsolateral plates, armed like the carinal plates), absence of interactinal plates (vs. one row of interactinal plates), small pedicellariae rarely found within the furrow (vs. pedicellariae frequently large and abun- dant on all surfaces). Madeira et al. (2019) also noted differences between juveniles and adults when they analyzed specimens (R 3–110 mm) from the Azores, however, they considered juvenile’s specimens with R <7 mm. The differences they noted were that the juveniles have only one dorsal (carinate) series (vs. three regular longitudinal series of primary plates), adambulacral plates generally bearing one long and flattened spine with no attached pedicellaria (vs. a second spine occasionally present, but restricted to the proximal region of the arms).

Coscinasterias tenuispina differs from C. acutispina by having the adambulacral spines frequently arranged in one row on the inner half of the arm (vs. two rows), from C. muricata by having 6–9 arms (vs. 9–11), and from C. calamaria by having crossed pedicellariae with a well-developed terminal tooth and straight pedicellaria with short stubs at the tips (vs. crossed pedicellariae with little or no development of an enlarged tooth, and straight pedicellariae with little or no modification at the tips).

Clark & Downey (1992) pointed out that the taxonomic status of the C. tenuispina specimens from Brazil is uncertain because of morphological differences in relation to specimens from other regions. For example, they noticed that the Brazilian (Cabo Frio, RJ) specimen that they examined has poorly developed straight pedicellariae, never large, and crossed pedicellariae with little or no sign of an enlarged tooth. Clark & Downey (1992) then suggested that C. calamaria could be a subspecies of C. tenuispina based on the morphological similarities observed among Brazilian and South African specimens. However, the Brazilian specimen that they examined had R 33 mm. Using molecular data, Waters & Roy (2003) confirmed the separation between Brazilian populations (n=3) and North Atlantic and Mediterranean populations, but they also found that C. calamaria is more closely related to C. acutispina than to C. tenuispina. An integrated taxonomic revision of juvenile and adult specimens of C. tenuispina along the Brazilian coast is needed to properly characterize its populations.