Amynthas corticis Blakemore et al. 2015

Amynthas corticis (Kinberg, 1867) and Amynthas diffringens (Baird, 1869): One or two peregrine species? The specific name, Amynthas diffringens, was once widely used instead of “ Amynthas corticis ”. Easton (1981) revalidated Amynthas corticis (Kinberg, 1867) and regarded Amynthas diffringens (Baird, 1869) as a synonym of A. corticis without providing any evidence or explanation. HPS examined the type specimens of A. diffringens archived in the Natural History Museum in London, UK. (BMNH 1869.1.2.1) and that of A. corticis in the Swedish Museum of Natural History in Stockholm, Sweden (SMNH-Type-1947) on 8 June 2016 and 13 December 2016, respectively. The type of A. corticis is a macerated aclitellate broken into two which bears hardly any morphological characteristics. In contrast, the nine mature specimens of A. diffringens types are morphologically recognizable. Meanwhile, the original description of A. corticis contains limited information including only setal number (40), segment number (114) and body length (68 mm) (Kinberg 1867, p. 102). It is doubtful regarding the synonymy between the two species. Blakemore (2013b) also points out this problem and further resurrects A. diffringens after examination of its types based on its genital markings anteriorly of spermathecal pores. However, among the nine mature specimens of A. diffringens types, three have no markings above spermathecal pores (Fig. 5G, H, I). Apparently, this single characteristic is subjected to individual variation and insufficient to distinguish a species. Moreover, we also found a specimen (GenBank accession number: JX290439) with markings anterior to spermathecal pores and markings adjacent to male porophores complying with those of the specimen with voucher number HY19 collected by Blakemore from Jeju, South Korea (Fig. 2B in Blakemore et al. 2015) (Fig. 2B, C). Blakemore et al. (2015, p. 4) made the following contradictory statements about this so-called Amynthas cf. corticis specimen with voucher number HY19: “The current specimen’s sample HY19 appears to conform to A. corticis group- 1 in the phylogram of Blakemore (2013: 101, fig. 1), e.g., 100% agreement with WM7 (A. corticis from Arataki Honey, N.Z.), “ Amynthas corticis ” (DQ224190.1 from Taiwan) and 100% “ Amynthas diffringens ” (EF077548.1, EF077550.1 from China), also with w59 (A. corticis from Incheon)=639/639 (100%) but differs slightly from w25 (“ A. diffringens?” from Jeju)=635/639 (99%). The current dissected sample agrees superficially with A. diffringens type as figured by Blakemore (2013d: fig. 9) and thus may be taken as representative of this taxon”. How can a specimen molecularly identified as A. corticis be taken as representative of A. diffringens? In addition, there is inconsistency about the identity of the specimen with DNA sample labeled as w25 by Blakemore (2013a, b). This specimen was identified as Amynthas corticis corticis (Kinberg, 1867) by Blakemore (2013a, p. 26) but as A. diffringens also by Blakemore (2013b, p. 123) (Table 2). Sequences of HY19 and our specimen with GenBank accession number JX290439 clustered with that of w25 (Fig. 3). However, this cluster also encompasses sequences from our other specimens without genital markings prior to spermathecal pores, i.e., sequences with GenBank accession numbers starting with “JX” except JX290439. Again, the presence or absence of the genital markings in front of spermathecal pores is individual variation which is far from being a diagnostic character for separating species. As demonstrated molecularly and morphologically, it is evident that there is only one valid species whether it is called A. corticis or A. diffringens. We suggest that Amynthas corticis (Kinberg, 1867) is an invalid specific name because: 1) the type is a juvenile and damaged, and cannot provide useful taxonomic information; 2) the original description does not provide useful taxonomic information, and no one knows what species it is. On the other hand, Amynthas diffringens (Baird, 1869) is a good species and it should be revalidated.