Struggling with shells: Drymaeus Albers, 1850 and Mesembrinus Albers, 1850 species (Mollusca, Gastropoda, Bulimulidae) from Peru—an illustrated checklist and descriptions of new species
Authors: Breure Abraham S. H. , Oroño Eugenia Salas , Ablett Jonathan D. , Vega-Luz Ricardo , Ávila Valentín Mogollón 
Published: November 2024

We critically examine Peruvian taxa belonging to the genera Drymaeus Albers, 1850 and Mesembrinus Albers, 1850, verify their original reference, and figure type materials, if located in and available from museums. We include additional photographs of non-type material when they are deemed useful to show variation. Original figures from the literature are reproduced for some species where photographs of type material are unavailable. We list precise localities in Peru where each species has been collected and map each species. Where possible, the ecoregions in which each species occurs are indicated. A brief history of research on Drymaeus and Mesembrinus from Peru is included. We recognise 94 valid species of Drymaeus and Mesembrinus. Additionally, we list 10 taxa that have been erroneously or doubtfully reported from Peru, 10 that are nomina inquirandi, and four species that have been transferred to another genus. We believe that our checklist may serve as a baseline document for further research. It can be seen as an intermediate step in the revision of these genera, which will require additional anatomical or molecular study to achieve a stable classification.
The following new species are introduced: Drymaeus araujoi Vega-Luz, Breure & Mogollón; Drymaeus nebulosum Breure & Ablett; Mesembrinus marmoratus Breure, Mogollón & Vega-Luz; Mesembrinus purpuralabrum Breure, Mogollón & Vega-Luz.
Two species are reported from the Peruvian malacofauna for the first time: Drymaeus fusoides (d’Orbigny, 1835) and Drymaeus tigrinus (S.I. da Costa, 1898).
We propose the following new combinations: Drymaeus combinai (Weyrauch, 1958); Mesembrinus acobambensis (Weyrauch, 1967); Mesembrinus anceps (Albers, 1854); Mesembrinus angulobasis (Pilsbry, 1944); Mesembrinus apicepunctata (Preston, 1914); Mesembrinus bequaerti (Weyrauch, 1956); Mesembrinus cactivorus (Broderip, 1832); Mesembrinus chrysomelas (E. von Martens, 1867); Mesembrinus clathratus (L. Pfeiffer, 1858); Mesembrinus coelestini (F. Haas, 1952); Mesembrinus cuzcoensis (Reeve, 1849); Mesembrinus cylindricus (S.I. da Costa, 1901); Mesembrinus eucosmetus (F. Haas, 1955); Mesembrinus farrisi (L. Pfeiffer, 1858); Mesembrinus inconspicuus (F. Haas, 1949); Mesembrinus lamas (Higgins, 1868); Mesembrinus laxostylus (Rolle, 1904); Mesembrinus leucomelas (Albers, 1854); Mesembrinus libertadensis (Pilsbry, 1898); Mesembrinus mexicanus (Lamarck, 1822); Mesembrinus miltochrous (Albers, 1854); Mesembrinus nigroapicatus (L. Pfeiffer, 1857); Mesembrinus paeteli (Albers, 1854); Mesembrinus pergracilis (Rolle, 1904); Mesembrinus phryne (L. Pfeiffer, 1863); Mesembrinus praetextus (Reeve, 1849); Mesembrinus pseudobesus (Breure, 1979); Mesembrinus pulcherrimus (H. Adams, 1867); Mesembrinus rosalbus (Pilsbry, 1932); Mesembrinus sachsei (Albers, 1854); Mesembrinus scitulus (Reeve, 1849); Mesembrinus silvanus (Zilch, 1953); Mesembrinus succinea (Pilsbry, 1901); Mesembrinus trujillensis (Philippi, 1867); Mesembrinus vespertinus (L. Pfeiffer, 1858); Mesembrinus zilchi (F. Haas, 1955); “Mesembrinus” vexillum (W. Wood Sr, 1828).
The following junior subjective synonyms are established: Drymaeus aurantiostomus Thompson & Deisler, 1982 = Drymaeus branneri F. Baker, 1914; Drymaeus eusteirus Pilsbry, 1944 = Bulimus chanchamayensis Hidalgo, 1870; Drymaeus (Mormus) expansus flavilabrum Weyrauch, 1967 = Bulimus expansus L. Pfeiffer, 1848; Drymaeus (Orodrymaeus) farrisi quadritaeniatus Weyrauch, 1956 = Bulimus farrisi Pfeiffer, 1858; Drymaeus (Drymaeus) latitesta F. Haas, 1952 = Bulimus icterostomus E. von Martens, 1901; Drymaeus beyerleanus mitchelli Dall 1912 = Bulimus beyerleanus Hupé 1857; Bulimus (Liostracus) fuscobasis E.A. Smith, 1877 = Bulimus rectilinearis L. Pfeiffer, 1855; Bulimus recedens L. Pfeiffer, 1864 = Bulimus serratus L. Pfeiffer, 1855; Gonyostomus subhybridus S.I. da Costa, 1906 = Otostomus pulcherrimus H. Adams, 1867; Mesembrinus (Ornatimormus) henrypilsbryi densestrigatus Weyrauch, 1958 = Mesembrinus (Ornatimormus) henrypilsbryi pichitacalugaënsis Weyrauch 1958 = Mesembrinus (Ornatimormus) henrypilsbryi Weyrauch, 1958 = Bulimulus pergracilis Rolle, 1904; Bulimus canarius L. Pfeiffer, 1867 = Bulimus trujillensis Philippi, 1867; Bulimus serenus Philippi, 1867 = “Mesembrinus” vexillum (Wood, 1828).
The generic placements of “Drymaeus” expansus (L. Pfeiffer, 1848) and “Mesembrinus” vexillum (W. Wood Sr, 1828) are provisionally pending future molecular study.
The need for additional research is demonstrated by the fact that for 15 species only imprecise localities are known, while for 33 species no records are available within the last 50 years.