Homalopoma boffii Marini, 1975

Cavallari, Daniel C., Salvador, Rodrigo B., Dornellas, Ana P. S. & Simone, Luiz R. L., 2019, Calliostomatidae, Colloniidae, Margaritidae, and Solariellidae (Gastropoda: Trochoidea) collected by the Marion Dufresne (MD 55) expedition in southeastern Brazil, with description of a new species of Calliostoma, Zootaxa 4609 (3), pp. 401-428 : 412

publication ID

https://doi.org/ 10.11646/zootaxa.4609.3.1

publication LSID

lsid:zoobank.org:pub:F38E6655-0EC4-48E1-A002-CAC599F3556D

persistent identifier

https://treatment.plazi.org/id/4A3387DC-FFB5-FFF7-FF6D-FC9D9DB0962B

treatment provided by

Plazi

scientific name

Homalopoma boffii Marini, 1975
status

 

Homalopoma boffii Marini, 1975 View in CoL

( Fig. 5 View FIGURE 5 K–N)

Homalopoma boffii Marini, 1975: 31 View in CoL , figs 1–3. Rios, 1985: 26, pl. 11, fig. 109; Rios, 1994: 43, pl. 14, fig. 145; Rios, 2009: 69, text fig. (switched with preceding species entry in error). Homalopoma boffi [sic]: Leal, 1991: 58; Benkendorfer & Soares-Gomes, 2009: 151.

Type material. Holotype: MZSP 18772 View Materials . Paratype: MZSP 18773 View Materials , 1 View Materials spm, from type locality .

Type locality. Brazil, off Rio Grande do Sul state, 31°08’S, 49°31’W, 183–253 m, R/V “ W. Besnard ” sta. 1858 (6/viii/1972) GoogleMaps .

Previously known distribution. Off southeastern Brazil, from São Paulo state to Rio Grande do Sul state ( Rios, 1994), including Trindade and Martim Vaz Islands, Montague and Columbia Seamounts ( Leal, 1991), 60–253 m (live specimens).

New records. Northeastern Brazil, off Ceará state, down to 260 m (shells only).

Habitat. Coralline and muddy bottoms.

Material examined. Brazil: São Paulo: off Santos , MZSP 36037 View Materials , 2 View Materials spm (local fishermen leg., xii/2002). Additional Non-MD55 material : Brazil: Ceará: 120 miles off Fortaleza, Canopus Bank , MZSP 53938 View Materials , 240– 260 m, 2 sh (viii/2005); MZSP 67303, 260 m, 7 sh (xi/2005); MZSP 70298, 260 m, 4 sh (xi/2005); MZSP 93535 View Materials , 60– 200 m, 2 sh (viii/2005); Rio Grande do Sul: types .

Measurements. 6–6½ whorls, H=8.7–10.0 mm, D=9.0– 10.4 mm (n=3).

Remarks. This seemingly rare species is usually characterized by its large, reddish shell, with strong rounded spiral cords and coarse nodulose sculpture starting on the teleoconch, but usually restricted to the first 3–4 whorls ( Marini 1975). The species, in fact, attains a larger size than reported in the original description (H=6.9, D=7.0 mm) and followed by the literature (e.g., Rios 1994, 2009; Rosenberg et al. 2009), reaching a shell height of 10.9 mm (MZSP 67303) and a maximum diameter of 10.8 mm (MZSP 36037) in non-MD 55 specimens we analyzed (from Canopus Bank, off northeastern Brazil).

Leal (1991) argued that the figures in the original description by Marini (1975: figs 1–3) were switched with those of another species, but the present examination of the type material showed that the holotype is the illustrated specimen: the proportions, sculpture and even the location of damaged areas are identical (MZSP 18772). Both type specimens are subadult shells, and the slight change in outline with age ( Fig. 5 N View FIGURE 5 ) may have caused confusion.

With its known distribution restricted to southern-southeastern Brazilian waters in recent works ( Leal 1991; Rios 1994, 2009), Homalopoma boffii is here revealed as more widely distributed than initially assumed, ranging as far as northeastern Brazil. Part of this newly reported range overlaps with that of Homalopoma linnei ( Dall, 1889) , which has also been found in the MD55 material (see below). Marini (1975) pointed out the similarity of these species, arguing that the main differences resided in the shell’s ground color (reddish as opposed to pure white in H. linnei ), number of spiral cords (fewer in H. linnei ), and overall size (~25% larger than H. linnei ). Except for the discrepancy in size, which is strongly consistent (and even amplified) in the assemblage examined here, the remaining dissimilarities are not confirmed: some specimens of H. boffii from Canopus are almost pure white, and the number of spiral cords on the body whorl is variable from 12 to 16 in both species. Even so, there are additional differences to be noted. In H. boffii , the protoconch is much less inflated, nearly flattened ( Fig. 5 M View FIGURE 5 ), and the very first teleoconch whorl already bears coarse, large nodules. The nodules themselves are always rounder and proportionally larger in H. boffii . Moreover, the shell of H. boffii has a more compact outline with a shorter spire, giving it a more globose profile ( Fig. 5 N View FIGURE 5 ). The suture is shallower in H. boffii , lacking the prominent, deep subsutural channel present in H. linnei . The spiral cords in H. boffii are proportionally wider, as are the interspaces, which in turn are shallower and less prominent than in H. linnei . The operculum in H. boffii is roughly circular ( Fig. 5 View FIGURE 5 K-L), as opposed to squarish in H. linnei ( Fig. 5 View FIGURE 5 I-J).

MZSP

Sao Paulo, Museu de Zoologia da Universidade de Sao Paulo

Kingdom

Animalia

Phylum

Mollusca

Class

Gastropoda

Order

Trochida

Family

Colloniidae

Genus

Homalopoma

Loc

Homalopoma boffii Marini, 1975

Cavallari, Daniel C., Salvador, Rodrigo B., Dornellas, Ana P. S. & Simone, Luiz R. L. 2019
2019
Loc

Homalopoma boffii

Rios, E. C. 2009: 69
Benkendorfer, G. & Soares-Gomes, A. 2009: 151
Rios, E. C. 1994: 43
Leal, J. H. 1991: 58
Rios, E. C. 1985: 26
Marini, A. C. 1975: 31
1975
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