Acanthochitona terezae Guerra-Junior, 1983

Jardim, Jaime A., De Almeida, Sergio M. & De Simone, Luiz R. L., 2022, Taxonomic study on the Polyplacophora (Chitonida: Ischnochitonidae et Acanthochitonidae) collected by the Marion Dufresne (MD 55) expedition, with description of a new species, Zoosystema 44 (5), pp. 151-157 : 154

Acanthochitona terezae Guerra-Junior, 1983

( Fig. 1F-J )

Acanthochitona terezae Guerra-Junior, 1983: 385-389 , figs 1-9. — Jardim et al. 2017: 491-497.

MARION DUFRESNE MATERIAL. — Brazil • 1 specimen; Espírito Santo, off Vitória ; 20°51’S, 33°45’W; 63 m; continental shelf; sta. DC 42; Bouchet, Leal & Métivier leg.; MNHN .

TYPE MATERIAL. — Probably lost ( Pimenta et al. 2014: 91).

Neotype. Brazil • 1 specimen, 4.5 × 1.0 mm; Espirito Santo; 20°50.9’S, 33°44.6’W; continental shelf; MZSP 115203 ( Jardim et al. 2017).

OTHER MATERIAL EXAMINED. — Brazil • 1 specimen, 4.0 × 1.1 mm; Espirito Santo, Trindade Island ; 20°30’55.6”S, 29°20’21.7”W; intertidal zone; MZSP 108309 • 3 specimens, 4.0 × 1.3 mm, 4.2 × 1.4 mm, 4.1 × 1.1 mm; Bahia, off Pratigi ; 13°30’13.0”S, 38°54’27.0”W; 0-1 m; MZSP 117509 • 1 specimen, 4.2 × 1.2 mm; Bahia, off Boipeba Island ; 13°29’33”S, 38°54’18”W; 0-3 m; MZSP 117524 • 1 specimen, 6.1 × 2.3 mm; Espirito Santo, Trindade Island ; 20°29’11.3”S, 29°20’15.8”W; 2.5 m; MZSP 131199 • 1 specimen, 3.1 × 0.9 mm; Pernambuco, Fernando de Noronha ; 3°48’55”S, 32°23’31”W; intertidal zone; MZSP 131605 • 2 specimens, 4.8 × 1.5 mm, 3.0 × 1.0 mm; Pernambuco, Fernando de Noronha ; 3°48’55”S, 32°23’31”W; 0-1 m; MZSP 131620 • 1 specimen, 5.0 × 1.9 mm; Espirito Santo, Trindade Island ; 20°29’18.7”S, 29°20’18.3”W; 0-2 m; MZSP 134383 .

TYPE LOCALITY. — Itapuã, Bahia, Brazil.

DISTRIBUTION. — Northeastern to southeastern Brazilian coast.

DIAGNOSIS. — Specimen size up to 4.0-4.5 × 1.0 mm. Intermediate valves of trapezoidal to oblong outline, subcarinate, slightly beaked. Jugum not well demarcated from pleurolateral areas. Tegmentum cream to beige, with white or green spots ( Fig. 1F-J ). Perinotum white, with some transverse orange bands ( Fig. 1F-G ). Tegmental pustules on pleurolateral areas round to oval, randomly arranged; pustules convex, bearing 4-7 pores on superior to median surface, lacking microaesthete pores. Tail valve with prominent, submedian mucro; postmucronal area concave. Perinotum covered with minute elongated spicules; spicule height about 8-9 times as long as wide (almost 90 µm in length), sculptured with longitudinal parallel fissures. Sutural tufts with elongated spicules, 350 to 450 µm long, with longitudinal fissures ( Jardim et al. 2017).

REMARKS

This species was described by Guerra-Junior (1983), and a neotype was designated by Jardim et al. (2017). Since the present specimen was preserved dry in a curled position, we were only able to obtain information on the sculpture, morphology of valves, and coloration of the dorsal surface. The valves and radula were not removed to avoid irreversible damage due to the fragile condition of the specimen. It also seems to be in an advanced stage of development compared to the specimens on which the original description was based, given that the marginal spicules on the perinotum are more developed and the anterior and posterior portions of the girdle are three times longer than the lateral one. Unfortunately, we were not able to locate the type material of A. terezae . According to the original description, the specimens should have been deposited in the Museu Nacional da Universidade Federal do Rio de Janeiro (MNRJ). However, the MNRJ staff has officially stated that the material is missing, and was most probably never deposited at all ( Pimenta et al. 2014). Therefore, comparisons were restricted to the information available in the original publications. The present records extend the distribution of A. terezae c. 1000 km southwards from the type locality, and the bathymetric range to a depth of 63 m.

Figures

FIG. 1. — A‒E, Stenoplax marcusi (Righi, 1971); A, B, lateral view; C, frontal view; D, dorsal view; E, posterior view; F-J. Acanthochitona terezae Guerra-Junior, 1983; F, G, lateral view; H, frontal view; I, dorsal view; J, posterior view; K‒O, Acanthochitona ciroi Righi, 1971; K, L, lateral view; M, frontal view; N, dorsal view; O, posterior view; P‒T, Acanthochitona oxum n. sp.; P‒Q, lateral view; R, frontal view; S, dorsal view; T, posterior view. Scale bars: 1 mm.