Acanthochitona avicula
Creators: name: Reyes-Gómez, Adriana
name: Vargas-Ponce, Ofelia
name: Galván-Villa, Cristian
name: Salgado-Barragán, José
name: Esqueda-González, Ma. Del Carmen
name: Ríos-Jara, Eduardo
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Polyplacophora
Chitonida
Acanthochitonidae
Acanthochitona
Acanthochitona avicula

description: Acanthochitona avicula (Carpenter, 1864)   
(Figures 3E, 10A–F)  
 Acanthochites avicula Carpenter 1864: 18–27. Chresonymy and synonymy in Watters (1990).   
 Type material. Lectotype by designation of Watters (1981), ANSP 349330.   
 Type Locality. Catalina Island, California, USA.   
 Material examined. One specimen, BL 9.6 mm.   
 Habitat. In the intertidal zone, in an exposed area with semi–wet rock mounds during low tide. The chiton was collected from the lower part of a rock semi–buried in sand with brown and red crusty algae patches.   
 Remarks. Acanthochitona avicula exhibits pustules with numerous (10–16) micraesthetes (Fig. 10D). The jugum exhibits a smooth surface with the micraesthetes openings visible (Figs. 10B, C). Girdle densely covered by curved, striated hyaline spicules (Fig. 10E). Radula with tricuspid major lateral teeth, the middle cusp is longer than the other two; minor lateral tooth very reduced; the central tooth is an elongated, apically hook–like plate (Fig. 10F).   
 Acanthochitona avicula was considered a synonym of A. angelica Dall, 1919 by several authors (Thorpe 1971; Abbott 1974; Kaas & Van Belle 1990). However, Smith (1977) indicated that the tegmentum color pattern of A. angelica does not correspond to the variations in color observed in A. avicula. Watters (1990) recognized both species as independent, considering the distribution of A. angelica in the Gulf of California, without specifying the sampling sites, which were somewhere in the Bahía de los Ángeles, Baja California (BC), and Islas Tres Marías, Nayarit. Moreover, he indicated that A. avicula has a wider distribution, from the Bahía la Choya to Puerto Peñasco, Sonora. He reported it as a common species in the intertidal and up to 20 m depth.   
 Watters (1990) provided a detailed morphological description of the Acanthochitona species from the eastern Pacific and provided for all of them SEM images of the valve pustules. This author showed that the jugum of A. avicula has 8 to 12 deep longitudinal grooves and that the pustules of the tegmentum are drop–shaped, densely covering the lateropleural areas. Conversely, A. angelica has a jugum with 7 to 10 more superficial grooves, the pustules are smaller and slightly rounded. The A. avicula specimen obtained in the present study showed that the pustules adjacent to the jugum are elongated, the peripheral pustules are less elongated, and the jugum is smooth on its center.
description: Published as part of Reyes-Gómez, Adriana, Vargas-Ponce, Ofelia, Galván-Villa, Cristian, Salgado-Barragán, José, Esqueda-González, Ma. Del Carmen & Ríos-Jara, Eduardo, 2023, Inventory of chiton species (Polyplacophora) from the rocky intertidal of the Northern Gulf of California, with an illustrated taxonomic key, pp. 147-178 in Zootaxa 5296 (2) on page 166, DOI: 10.11646/zootaxa.5296.2.2, http://zenodo.org/record/7973065