Aclis verrilli Bartsch, 1911

Souza, Leonardo Santos De, Araújo, Tarciso Almeida De & Pimenta, Alexandre Dias, 2024, Taxonomic review of Aclis Lóven, 1846 (Gastropoda, Eulimidae) from Brazil with notes on other congeners from the western Atlantic and Saint Helena, Zootaxa 5433 (4), pp. 451-499 : 482-484

Aclis verrilli Bartsch, 1911

Figs 18E – I

Aclis verrilli Bartsch, 1911: 437 , pl. 59, Fig. 6 .

Hemiaclis verrilli ― Bartsch 1947: 17, pl. 4, Fig. 5 .

Hemiaclis tanneri Bartsch, 1947: 23 , pl. 5 Fig. 1 .

Type material. Holotype (herein examined): USNM 44811 .

Type locality. USA: New Jersey state: off Martha’s Vineyard , USFC sta. 894; 39°53′N, 70°58′W, 668 m; R/ V Fish Hawk col., 02/x/1880 .

Material examined. The holotype and: holotype of Aclis tanneri : USNM 417444 :

USA: New Jersey state: Hudson Canyon , USFC sta. 2234; 39.15 N, 70.0542 W, 1481 m; R/ V Fish Hawk col., 13/ix/1884 .

Remarks. MolluscaBase (2021a) considers Aclis tenuis as the senior synonymy of a group of very similar species described from material of the USFC from New Jersey and Georgia localities: Aclis verrilli Bartsch, 1911 , Aclis fernandinae Dall, 1927 and Aclis tanneri Bartsch, 1947 . Such synonymy was proposed by Bouchet & Waren (1983: 306), who also speculated about the possible synonymy with A. walleri ; however, the authors were somewhat dubious about the occurrence of A. walleri in West Atlantic and stated that the gap of distribution should be filled for a better comprehension. The occurrence of A. walleri in the western Atlantic (recorded by Verrill, 1880: 391; 1882: 528) was also contested by Bartsch (1911: 438) who considered that the material studied by Verrill (1880, 1882: 377), from the USFC are distinct from A. walleri and he described Aclis verrilli .

In the present study, all types of the above names were examined, and some conclusions could be taken about the validity of them.

Aclis verrilli ( Fig. 18E–I ) is a valid species and can be distinguished from A. tenuis ( Fig. 18A–B ) because it has a considerably narrower and multispiral protoconch, besides a faster increase in diameter in the teleoconch. Aclis tanneri ( Fig. 18H–I ), by the other hand, cannot be distinguished from A. verrilli .

The shell of Aclis tenuis and Aclis verrilli are considerably wider and conical, while A. fernandinae ( Fig. 18C–D ) has a more cylindrical shape. Sexual dimorphism is known in Eulimidae with females usually bigger than males ( Warén 1983), but until we have evidence for this in Aclis we consider both as valid species.

Figures

FIGURE 1. Terminology of some of the shell features used in descriptions in the present study. A. Microscopic spiral striae of the teleoconch indicated by arrows. B. Spiral keels of the teleoconch indicated by arrows. C. Umbilical fissure indicated by arrow. D. Umbilicus indicated by arrow.

FIGURE 5. Aclis kanelaAbsalão, 2009. A, D–G. MNRJ 28293. B–C. MNRJ 26713. A–C. Shell in frontal view; rectangle in A indicates detail in E. D. Detail of body whorl in frontal view. E, F. Detail of teleoconch sculpture; rectangle in E indicates detail in F. G. Detail of apical whorls. Scale bars: A–C. 1 mm; D. 500 μm; E–F. 50 μm; G. 200 μm.

FIGURE 6. Aclis sp. 1: MNRJ 33505. A. Shell in frontal view. B. Apical whorls: double arrows indicate microscopic and sigmoid axial line at the protoconch surface, single bottom arrow indicate microscopic spiral striae at the teleoconch surface. C. Body whorl. Scale bars: A. 1 mm; B. 200 μm; C. 500 μm.

FIGURE 18. A, B. Aclis tenuis Verrill, 1882: Holotype, USNM 44821. A. Shell in frontal view. B. Shell in lateral view. C, D. Aclis fernandinae Dall, 1927: Holotype, USNM 108047. C. Shell in frontal view. D. Protoconch in apical view. E–I. Aclis verrilli Bartsch, 1911: E–G. Holotype, USNM 44811; H–I. Holotype of Aclis tanneri (Bartsch, 1947), USNM 417444. E, I. Shell in frontal view. F, H. Shell in lateral view. G. Detail of apical whorls. Scale bars: A–C, E–F, H–I. 1 mm; D, G. 200 μm. Credits: C–D. USNM