Revision of Bostryx stelzneri complex

Miranda & Cuezzo have now published a long awaited paper, presenting a revision of a species group from northern Argentina, the Bostryx stelzneri complex. This paper partly resulted from Miranda’s Ph.D. thesis work.

The abstract reads: “The Bostryx stelzneri species complex is taxonomically reviewed with the description of a new species. This complex is formed by Bostryx stelzneri (Dohrn, 1875), B. peristomatus (Doering, 1879), B. scaber (Parodiz, 1948) and Bostryx roselleus n. sp., all distributed in Argentina. Bostryx peristomatus and B. scaber are elevated to specific status on the basis of morphological characters. This complex has the spire less than half the total shell height and the aperture higher in relation to total shell height than in any other species of the genus. Traditional shell morphometry and a geometric morphometric analysis were used to document shell variation in size and shape among species. Radula, jaw and shell morphology were examined with SEM. All species in the complex are described or redescribed using new morphological information. In this species complex, pallial organs are very similar among species and vary only in the degree of opening of the secondary ureter. The genitalia differ in the relative proportion of organs, such as length of vagina relative to free oviduct and penis or epiphallus length relative to penis length. Sculpture of the inner wall of the flagellum and epiphallus is similar in all species studied, whereas sculpture of the inner wall of the penis is variable. Geometric morphometric analysis allows an objective interpretation of shell shape variation detecting differences in shape components irrespective of the differences in size between Bostryx Troschel, 1847 species of the stelzneri group.”

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In the introduction (p. 74) I saw a sentence that shows a misinterpretation of my 1979 thesis. “Breure (1979) listed 23 species of Bostryx in Argentina, while Miquel (1993, 1995) recognised only 13 valid species using shell morphology similarities to justify his synonymic actions.” The misinterpretation lies within the suggestion that in my thesis the species lists under each genus were lists of valid species. There were not; my thesis was a revision of the genera within the subfamily (now regarded as family Bulimulidae), the lists of ‘species’ under each genus were actually a list of taxon names from literature that had been placed in the genus. Nothing less, nothing more. The later work of Miquel was a more detailed taxonomic revision of the species from Argentina; of the available taxa he considered 10 as junior subjective synonyms, and thus ended up with 13 species.
Finally, in the discussion (p. 89), the authors state “he [Breure 1979] did not describe the inner penial anatomy which is unknown in all Bostryx species”. Possibly the authors had the Argentinean species in mind? In Breure 1979: fig. 63-64 schematic reconstructions of two (Peruvian) Bostryx species are given, while in a previous paper the histology is described of the inner genitalia from nine Bostryx species, among which B. stelzneri (Breure 1978: 127-128). But indeed, “the reproductive system is very simple in comparison to other genera of Bulimulidae” as the authors state (p. 89).

In this paper Miranda & Cuezzo have thoroughly studied all available material at hand, and propose a new classification. The 13 species have been reduced to four, with additionally a number of “morphological or population variations” within Bostryx stelzneri.

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References:

Breure, A. S. H. 1978. Notes on and descriptions of Bulimulidae (Mollusca, Gastropoda). — Zoologische Verhandelingen 164: 1–255.
Breure, A. S. H. 1979. Systematics, Phylogeny and Zoogeography of Bulimulinae (Mollusca). — Zoologische Verhandelingen 216: 1–98.
Miquel, S. E. 1993. Las especies del género Bostryx Troschel, 1847 en la República Argentina (1ra. parte) (Gastropoda Stylom- matophora: Bulimulidae). — Archiv für Molluskenkunde 121: 157–171.
Miquel, S. E. 1995. Las especies del género Bostryx Troschel, 1847 en la República Argentina (2da. y última parte) (Gastropoda Sty- lommatophora: Bulimulidae). —Archiv für Molluskenkunde 124: 119–127.
Miranda, M.J. & Cuezzo, M.G. (2014). Taxonomic revision of the Bostryx stelzneri species complex, with description of a new species (Gastropoda: Orthalicoidea: Bulimulidae). — American Malacological Bulletin 32: 74-93.

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