Lepidochitona beanii (Carpenter, 1857)

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, Zootaxa 5296 (2), pp. 147-178 : 162-164

Lepidochitona beanii (Carpenter, 1857)

( Figures 3B , 8I–O )

Lepidopleurus beanii Carpenter, 1857: 209–229 . Chresonymy and synonymy in Ferreira (1982).

Type material. Lectotype, designated by Keen (1968), Carpenter´s Mazatlán collection, LACM tablet 905.

Type locality. Mazatlán , Sinaloa, México .

Material examined. Ten specimens, BL 4.7–8.5 mm.

Habitat. In the upper intertidal on medium–sized and small rocks, buried in sand.

Remarks. Lepidochitona beanii has a microgranular sculpture in all valves ( Figs. 8I–M ), lateral areas delimited by a shallow depression ( Fig. 8L ). Girdle densely covered by tiny spicules and tufts of hyaline curved spicules, bunched in groups of 3–5 located near the sutural areas of the valves ( Figs. 8I–J ). Radula with tricuspid major lateral tooth, minor lateral tooth long and narrow, shorter than the central tooth, which is a sub–rectangular, long plate ( Figs. 8N–O ).

Ferreira (1982) recorded specimens from Baja California (he did not specify the exact locality) with a maximum size of 11.7 mm, and with varied tegmentum colors (pink, cream, and light "salmon" color). Ferreira (1982) reported that hyaline girdle spicules are lacking in small individuals (BL 4.5 mm) and concluded that these structures develop in the last phase of the juvenile stage (this cannot be confirmed herein, see below). Kaas & Van Belle (1985a) reported that L. beanii has been collected from the intertidal to up to 230 m depth, showing a continuous distribution from southern California to Perú, including the Gulf of California. García-Ríos & Álvarez-Ruiz (2007) reported L. beanii from La Paz, Baja California Sur (BCS). There are no recent reports from the type locality, Mazatlán, Sinaloa.

We found that hyaline spicules are present even in small specimens collected at Bahía Kino (BL 3.6 mm, see Fig. 8I ) and La Paz (BL 3.1 mm, see Fig. 8J ). Smaller specimens also showed hyaline spicules, while larger ones showed evidence of many broken spicules. Therefore, Ferreira's (1982) hypothesis regarding the late ontogenetic development of the spicules could not be confirmed.

Figures

FIGURE 3. Chiton species obtained from the Northern Gulf of California. A. Dorsal and lateral view of Dendrochiton lirulatus CUCBACM 00479. B. Dorsal view of Lepidochitona beanii CUCBACM 00486. C. Dorsal and lateral view of Nutallina crossota CUCBACM 00488. D. Dorsal view of Chiton virgulatus CUCBACM 00491. E. Dorsal view of Acanthochitona avicula CUCBACM 00494. F. Dorsal view of Acanthochitona exquisita CUCBACM 00497.

FIGURE 8. A–H. Scanning electron microscope images of Dendrochiton lirulatus CUCBACM 00479. A. Dorsal view of head valve. B. Dorsal view of intermediate valve IV. C. Dorsal view of tail valve. D. Detail of valve IV aesthetes of central area. E. Section of girdle in dorsal view. F. Detail of dorsal girdle elements. G. Detail of dorsal girdle spicules. H. Radular teeth. I–O. Scanning electron microscope images of Lepidochitona beanii CUCBACM 00486. I. Dorsal view of a whole specimen of BL 3.6 mm. J. Dorsal view of a whole specimen of BL 3.1 mm. K. Dorsal view of head valve. L. Dorsal view of intermediate valve IV. M. Dorsal view of tail valve. N. Radular teeth. O. Detail of central and minor lateral radular teeth.