Orthopleura Spinola, 1845

Reily, Brian H., 2020, Imbriea nom. nov., a replacement name for Orthopleura Imbrie, 1959 (Brachiopoda), Zootaxa 4894 (1), pp. 143-145 : 143-144

Genus Orthopleura Spinola, 1845

Type species: Tillus damicornis Fabricius, 1798: 117 by subsequent designation in Gorham 1877: 426, see also Article 69.1 of the Code.

Bousquet (2016: 511) addressed the correct publication date of this genus, which has been incorrectly reported in past literature as “1844” based on the imprint date on the title page.

Spinola (1845: 80) erected this genus to contain two described and one new species— Tillus damicornis Fabricius, 1798 , Dermestes sanguinicollis Fabricius, 1787 and Orthopleura quadraticollis Spinola, 1845 . Except for the type species as designated by Gorham (1877), all other taxa originally included in this genus—and others subsequently included in this genus by Corporaal (1950) in his catalogue of the family—have since been transferred into different genera (see Barr 1976, Opitz 2013, Winkler 1979, and Winkler 1984) leaving Orthopleura Spinola monotypic.

Fabricius (1798) originally described Tillus damicornis from North American specimens in the collection of John Dietrich Herschel. The fate of Herschel’s collection—including the types of this species—is unknown. It is possible that these specimens were subsumed into other collections or they may have been destroyed ( Madge 1994). Fabricius (1798) provides only a brief description of this species which lacks sufficient detail to unambiguously determine its identity. However, a few particulars in Fabricius’ original work are worth noting. First, the antennal club of this clerid species, which the original description claims to be composed of two, flattened, acuminate segments, is atypical of the North American clerofauna and suggests either an otherwise unknown genus or a type specimen with missing terminal antennomeres. Second, the comparison of Tillus damicornis to an established junior synonym of Dermestodes sanguinicollis (Fabricius, 1787) (see Winker 1979)—“[ Tillus ] weberi … Statura omnino praecedentis [i.e. Tillus damicornis ] at alius et maior ”—establishes the morphological similarity of these two species and suggests that orthopleurines were within the scope of Fabricius’ taxonomic concept of Tillus Olivier, 1790 .

There are four specimens labeled as Orthopleura damicornis in Spinola’s collection ( Ekis 1975). This is presumably the material which Spinola examined when he established the genus. Spinola (1845) was not explicit about the origin of these specimens, and he habitually did not attach labels to his pinned material ( Ekis 1975). Therefore, there appears to be no strong evidence that these specimens are—or are not—the types described by Fabricius. Spinola’s description and illustrations of this species appear to be of a North American orthopleurine similar in morphology and coloration to Neorthopleurra thoracica (Say, 1823) sec. Barr 1976.

However, Barr (1976: 2) reported that the type specimens of Orthopleura damicornis ( Fabricius, 1798) —presumably referring to the specimens in Spinola’s collection—are not congeneric with other species included in the genus by Corporaal (1950: 266) and used this claim to justify erection of the genus Neorthopleura Barr. It is worth noting that Barr provided no evidence to support this claim—i.e. no redescription of Orthopleura Spinola , no inclusion of this genus in keys, no discussion of diagnostic characters used for distinguishing this genus from morphologically similar taxa, and no references to any prior works that suggested this genus as distinct—pinning the validity of his newly erected taxon solely upon the author’s expert opinion. Subsequent authors either followed Barr’s classification or simply did not include Orthopleura Spinola in their revisionary works.

Despite the uncertainty regarding type material of the type species of Orthopleura Spinola , Article 70.1 of the Code is clear on the validity of the establishment of this genus, stating that “[i]t is to be assumed, in the absence of clear evidence to the contrary, that an author has identified the species correctly when he or she… includes a previously established nominal species in a new nominal genus.”

While the genus Orthopleura Spinola is demonstrably valid, a great deal of work remains to stabilize the taxonomy of the type species and of other, morphologically similar taxa. A complete modern revision of Orthopleura Spinola is needed and would include, minimally, (1) a thorough redescription of Spinola’s types (Museo Regionale de Scienze Naturali, Turin) and (2) evaluation of this material in relation to Fabricius’ original description, (3) an exhaustive search of the Fabrician material and their past and present repositories (Zoologisk Museum, Copenhagen and Zoologische Museum Kiel, respectively) for types matching Fabricius’ description, (4) the formal designation of either lectotypes or neotypes as per the specifications of the Code in order to stabilize the identity of Tillus damicornis Fabricius , and (5) an informed evaluation of the validity of other orthopleurine genera, including some discussion of diagnostic characters needed to separate Orthopleura Spinola from other, similar genera.