Naesiotus arnaldoi ( Lanzieri and Rezende 1971 )

Salvador, Rodrigo B., Cunha, Carlo M. & Simone, Luiz Ricardo L., 2013, Taxonomic revision of the orthalicid land snails (Pulmonata: Stylommatophora) from Trindade Island, Brazil, Journal of Natural History (J. Nat. Hist.) 47 (13 - 14), pp. 949-961 : 953-954

Naesiotus arnaldoi ( Lanzieri and Rezende 1971)

( Figures 2G–L )

Protoglyptus arnaldoi Lanzieri and Rezende 1971: 255 (figs 1–45).

Naesiotus arnaldoi: Breure and Coppois 1978 ; Breure 1979; Salgado and Coelho 2003; Simone 2006: 125 (fig. 395).

Holotype

MNRJ 3105 (examined; Figure 2G ).

Paratypes

MNRJ 3105 (examined; Figure 2K ) .

Type locality

Desejado Peak (Pico do Desejado), Trindade Island.

Distribution

Endemic to Trindade Island.

Etymology

Species dedicated to Prof. Arnaldo C.S. Coelho (MNRJ).

Diagnosis

Shell narrow. Aperture more anteroposteriorly elongated. Presence of a weak callus on parietal region of aperture. Teleoconch sculptured by fine prosocline and irregular axial ribs.

Redescription

Shell small, conical to fusiform; five whorls. Spire angle ∼55 ◦. Greatest width on body whorl; width about one-half shell length. Colour dirty white to light brown, somewhat translucent. Protoconch of 11 / 2 whorl, sculptured by weak regularly spaced undulating parallel axial riblets. Teleoconch smooth, except for growth lines. Suture weakly marked, slightly oblique (diagonal) to columellar axis. Whorls profile slightly convex. Aperture slightly prosocline, large, oval, somewhat anteroposteriorly elongated; about two-fifths shell length, about one-half shell width. Weak callus on parietal region of aperture. Lamellae or teeth absent. Lip thin, simple, non-reflected, with exception of upper columellar region (reflected and covering umbilicus). Body whorl about two-thirds shell length. Umbilicus rimate, almost imperforate.

Measurements (in mm)

Holotype. H = 9.5; D = 5.5; S = 4.0; S′ = 3.2; h = 5.1; d = 3.2.

Mean (n = 68). H = 11.0 ± 0.6 (max 12.4; min 9.7); D = 5.7 ± 0.3 (max 6.3; min 5.1); S = 5.7 ± 0.4 (max 6.6; min 5.0); S′ = 3.6 ± 0.3 (max 4.6; min 2.9); h = 5.1 ± 0.4 (max 6.3; min 4.4); d = 3.2 ± 0.2 (max 3.8; min 2.6).

Material analysed

BRAZIL. Southwest Trindade Island : MNHN (eight shells); MZSP (two shells). Andradas Beach ( Praia dos Andradas ): MZSP 101244 (80 shells). Desejado Peak (Pico do Desejado): MNRJ 3105 (holotype and paratypes, 73 specimens, 145 shells) .

Remarks

Naesiotus arnaldoi falls well within the morphological range of the genus, both with regard to its shell, specially the sculpture pattern of the protoconch ( Figure 2L ), which is typical of the genus ( Breure 1979), and to its radula and genitalia (described by Lanzieri and Rezende 1971), which compare fittingly with the anatomical work of Breure and Coppois (1978) on the genus Naesiotus . Lanzieri and Rezende (1971) presented a thorough comparison of the shell of N. arnaldoi to other species in the genus, highlighting its similarities with N. eudioptus (Ihering in Pilsbry, 1897) from Southern Brazil and Paraguay ( Simone 2006). Naesiotus arnaldoi can be differentiated from other Naesiotus species mainly by its narrower shell profile and its large and slightly anteroposteriorly elongated aperture. Other diagnostic features include a weak callus on the parietal region of the aperture and the sculpture pattern of the teleoconch, but these features can also be found in some other species, like N. eudioptus and N. lopesi (Rezende, Lanzieri and Inada, 1972) , respectively.

Figures

Figure 2. (A–C) Bulimulus brunoi (holotype, MNRJ 1128; H = 19.4 mm). (D) B. brunoi (MNRJ 1129; H = 20.7 mm). (E, F) B. brunoi, protoconch and teleoconch sculpture (MZSP 101245). (G) Naesiotus arnaldoi (holotype, MNRJ 3105; H = 9.5 mm). (H–J) N. arnaldoi (MZSP 104740; H = 10.8 mm). (K) N. arnaldoi (paratype, MNRJ 3105; H = 10 mm). (L) N. arnaldoi, protoconch sculpture (MZSP 101244). (M–O) Vegrandinia trindadensis (MZSP 104742; 5.2 mm). (P, Q) V. trindadensis (holotype, MNRJ 3711; H = 7 mm). (R, S) V. trindadensis (MZSP 104743), (R) protoconch sculpture, (S) broken aperture showing the lamellae.