Callistochiton elenensis
Creators: name: Reyes-Gómez, Adriana
name: Flores-Garza, Rafael
name: Galeana-Rebolledo, Lizeth
name: Hernández-Vera, Gerardo
name: Galván-Villa, Cristian M.
name: Torreblanca-Ramírez, Carmina
name: Flores-Rodríguez, Pedro
name: García-Ibañez, Sergio
name: Ríos-Jara, Eduardo
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Polyplacophora
Chitonida
Callistoplacidae
Callistochiton
Callistochiton elenensis

description: Callistochiton elenensis (G. B. Sowerby I, 1832)
Figures 2G, 6J–K, 7A–K, 8A–B
Distribution. Throughout the Gulf of California, México (including Sinaloa, Sonora, Baja California and Baja California Sur) along Central America Punta Ancón, Santa Elena, Ecuador (Reyes-Gómez 2016; Kaas & Van Belle 1994).
Type specimens. Kaas & Van Belle (1994) designated the lectotype from BMNH, H. Cuming collection, number 1829/1.
Type Locality. Puerto Santa Elena, Panamá.
Material examined. 40 specimens, maximum size of 14.8 mm long, 9.2 mm wide. L (n=4); D (n=5); M (n=5); N (n=5); A (n=7); K (n=6); F (n=8).
Habitat. This species was observed to occur in two habitats: intertidal with high wave energy areas attached on medium rocks commonly covered with green and brown algae, and in shallow subtidal (3–8 m depth) on small rocks where it seems to be most abundant. This species was collected with Callistoplax retusa, Chaetopleura hanselmani and Stenoplax limaciformis in subtidal depths. The juveniles of C. elenensis were collected buried in sand on smaller rocks at 6–12 m depth.
Remarks. Callistochiton elenensis exhibits a wide range from the Gulf of California to Ecuador (Kaas & Van Belle 1994). In México, it has been recorded as common in Baja California Sur (García-Ríos & Álvarez-Ruiz 2007) and within the southern Gulf of California in Sinaloa (Ortiz-Arellano & Flores-Campaña 2008). This species is common in Acapulco and northern Guerrero, and according to Reyes-Gómez (2016) it is also common in Jalisco.
Comparing our specimens with the lectotype (Santa Elena, Panamá), described and illustrated by Kaas & Van Belle (1994), we identified differences in body size and in the number of the pustule rows of the lateral areas as well as the thickening of its nodules. Specimens from Guerrero showed smaller body size reaching up to 14.8 mm and displayed fewer ribs than the lectotype, with 8 ribs on the head valve and 7–9 on the tail valve; the nodules or knobs of the ribs also appeared smaller and more rounded. Examination of specimens from La Paz, Baja California Sur were up to around 20 mm in body length and usually displayed 9 ribs in the head valve and the tail valve has large, thick nodules or knobs. The specimens from Mazatlán showed similarities with La Paz chitons, reaching a large body length (17 mm) and in general, the valve ribs thicken as the specimens reach its maximum size (Fig. 20L–M).
Kaas & Van Belle (1994: fig. 67) presented drawings of the radular plates of lectotype of C. elenensis, in which they depicted the central tooth as a large rectangular plate, anteriorly wider than at its base and the minor lateral has a similar shape but is smaller. A closer examination to the radular teeth of specimens from different localities along the Mexican Pacific revealed morphological variation. The central tooth of chitons from La Paz (Playa Balandra, 19.2 mm length) showed a rectangular plate and the minor lateral tooth had a small sub-rectangular shape. The specimens from Playa Manzanillo, Guerrero (Acapulco) possess an oval central tooth (Fig. 7K) and a smaller bicuspid minor tooth. However, specimens from northern Guerrero (Troncones) have a central tooth that is sub-rectangular in shape and others irregularly sub-rectangular (Fig. 8A, B) and the minor lateral has an irregular bicuspid sub-triangular plate. Little is known about the radular features from specimens of other regions along the latitudinal range of this species. The radular central teeth variation observed in Guerrero chitons, may indicate intraspecific variability, which requires further investigation.
description: Published as part of Reyes-Gómez, Adriana, Flores-Garza, Rafael, Galeana-Rebolledo, Lizeth, Hernández-Vera, Gerardo, Galván-Villa, Cristian M., Torreblanca-Ramírez, Carmina, Flores-Rodríguez, Pedro, García-Ibañez, Sergio & Ríos-Jara, Eduardo, 2022, Intertidal chitons (Mollusca: Polyplacophora) from the rocky coastline of Guerrero, México, with the description of a new species, pp. 451-492 in Zootaxa 5155 (4) on page 465, DOI: 10.11646/zootaxa.5155.4.1, http://zenodo.org/record/6691172