Peckia

Buenaventura, Eliana & Pape, Thomas, 2015, Phylogeny of the Peckia-genus group: evolution of male genitalia in the major necrophagous guild of Neotropical flesh flies (Diptera: Sarcophagidae), Organisms Diversity & Evolution (New York, N. Y.) 15 (2), pp. 301-331 : 324-326

Genus Peckia

Peckia was recovered as monophyletic in analyses of the morphological data ( Figs. 8 , S1–3) but as paraphyletic in the molecular-based analyses ( Figs. 9 , S 4 ). Two uniquely derived apomorphies supported the monophyly of Peckia , these are (1) the presence of a fringe of hair-like setae extending to the posterior corner of the lower calypter, and (2) the reduction of the capitis.

Pape (1996) proposed five character states as generic diagnosis of Peckia in his Catalogue of the Sarcophagidae of the World; all of them were included in our character matrix. The first character state proposed by Pape (1996) was the lower calypter with a fringe of long hair-like setae along the outer margin extending to—or almost to—its posterior corner, which is one of the two uniquely derived apomorphies of the genus. The second character state was the median stylus reduced, here re-interpreted as a reduction of both the median process as well as the capitis, of which the former is shared with Helicobia and Sarcophaga and therefore does not diagnose Peckia . The third character state proposed by Pape (1996) was the lateral styli filiform, which is found only in species of the subgenera Euboettcheria , Peckia , and Sarcodexia (Fig. 2h), but not in Pattonella or Squamatodes , in which the lateral styli are shorter and wider (Fig. 2f, g). The fourth character state was the juxta reduced or not developed. Here, the juxta is considered as present in Peckia , according to the definition of this structure by both Giroux et al. (2010) and our study. The last diagnostic character state of Pape (1996) was the female abdominal T6 divided into two lateral plates door-like closing the terminalia, which is present in all scored species of Peckia except for Squamatodes and some Sarcodexia , but more data is needed to allow a credible optimization of this character on the trees.

In the present study, two hypotheses of the in- or exclusion of particular species in Peckia are tested. The first one is the hypothesis of Sarcophaga adolenda as part of Peckia (s. str.) ( Pape 1996), which with strong support is refuted here, since this species is consistently falling outside Peckia and grouping with R. retrocita as proposed by Buenaventura and Pape (2013). The second hypothesis refers to the phylogenetic position of Sarcodexia lambens . Already Roback (1954) suggested that Peckia (his Paraphrissopoda and Euboettcheria ) could be paraphyletic with regard to S. lambens . Pape (1996) treated Sarcodexia as a genus separate from Peckia , which later was supported by Giroux et al. (2010) in their morphology-based phylogenetic study, where S. lambens came out as a sister taxon of the genus Titanogrypa . In a molecular-based phylogenetic assessment of calyptrate flies, Kutty et al. (2010) found ( Sarcodexia + Villegasia ) emerging as the sister group of a paraphyletic Peckia . In short, available evidence prior to our study points to Sarcodexia as being either part of Peckia or cladistically very close to it. Recently in our taxonomic work on the genus Peckia ( Buenaventura and Pape 2013) , we considered S. lambens as part of this genus, and we redefined Sarcodexia as a subgenus to contain S. lambens plus other species previously considered as part of the subgenus Euboettcheria . Here, this hypothesis is tested in a phylogenetic context, and as outcome the monophyly of the genus Peckia as well as all subgenera that currently belong to it (sensu Buenaventura and Pape 2013) is confirmed. Thus, the subgeneric division proposed by Pape (1996) is maintained, but with Sarcodexia transferred into Peckia as an additional subgenus.

Our morphological data strongly indicated the monophyly of all subgenera of Peckia . Similarly, our molecular analyses confirmed the monophyly of the subgenus Peckia (s. str.), although it was not able to recover Sarcodexia as monophyletic. In our strongest phylogenetic hypothesis ( Fig. 8 ) that is based on morphological data, species of Peckia were arranged in two main clades, one clade consisting of the subgenera Squamatodes and Pattonella and another with the subgenera Euboettcheria , Peckia , and Sarcodexia . These two clades showed stability and robustness in all morphology-based trees under all character-coding schemes, and they received generally strong branch supports ( Table 2).

The clade ( Squamatodes + Pattonella ) was supported by four character states: (1) setae on prosternum and/or posterior surface of hind coxa yellow or light brown, (2) postalar wall with anterior setae white or yellow, (3) sternites I and II with yellow or light brown setae, and (4) juxta globose (except in P. (Squamatodes) ingens ). The clade (( Euboettcheria + Sarcodexia ) + Peckia ) was supported by four character states: (1) cercal prong with dorsal surface gently bent, (2) demarcation between juxta and distiphallus reduced, (3) juxta long to extremely long ( Figs. 5c–e and 4d–f ), (4) lateral styli elongat- ed and filiform (Fig. 3f). The sister-group relationship ( Sarcodexia + Euboettcheria ) was supported by three character states: (1) surstylus squared, (2) demarcation between vesica and distiphallus absent, and (3) vesica small. The monophyly of subgenus Sarcodexia as defined by Buenaventura and Pape (2013) was only supported by morphological evidence. The sister-group relationship between Euboettcheria and Paraphrissopoda (= subgenus Peckia ) proposed by Lopes (1983) was not supported in our analyses.

We observed a considerably more elongated and specialized juxta in the clade composed of Euboettcheria , Peckia , and Sarcodexia than in other clades ( Fig. 10 ). Some juxtal character states found in species of Sarcodexia ( Figs. 6 and 7 ) can be seen as intermediate between the juxta in subgenera Euboettcheria and Peckia (s. str.). For instance, the configuration of the juxta in Peckia (Sarcodexia) dominicana (Lopes, 1982) ( Fig. 7c ) and Peckia (Sarcodexia) aequata (Wulp, 1895) ( Fig. 7e ) is especially similar to the shape of the juxta of species of the subgenus Peckia and Euboettcheria , respectively.

Our morphology-based analyses supported Pape’ s (1996) subgeneric classification for Peckia . The monophyly of the subgenus Euboettcheria was supported by nine uniquely derived apomorphies, all of them in the male terminalia, some of them are the cercal prong with a posterior swelling, the pregonite strongly curved and proximally with folded margin ( Fig. 11), and the very conspicuous juxta resembling a long tube ( Fig. 5c ). Pape (1996) proposed the ctenidium in the male mid femur for a definition of this subgenus, but since we also observed this structure in some species of the subgenus Sarcodexia , and also in the genera Oxysarcodexia , Ravinia , and Villegasia , it is not considered as diagnostic for Euboettcheria .

Eight character states from the male genitalia and other body regions supported the monophyly of Pattonella , two of them are the abdominal tergites III and IV with dorsal length greater than the ventral length in lateral view ( Fig. 12 ) and a characteristic tubular vesica ( Fig. 13 ). Giroux et al. (2010) homologized the vesica in P. (Pattonella) intermutans with a pair of small apophyses on the anterior margin of the paraphallus (see Giroux et al. 2010: fig. 13e). However, these small apophyses were found in P. (Pattonella) intermutans only. Instead, we homologized the vesica in species of Pattonella with a tubular structure attached to the paraphallic anterior margin. The point of attachment to the distiphallus divides the tubular structure of the vesica into a distal long segment, and shorter proximal part ( Fig. 13 ).

The monophyly of the subgenus Peckia (s. str.) was supported by five uniquely derived apomorphies including the presence of a surstylus less sclerotized postero-apically (see Buenaventura and Pape 2013: fig. 21).

Subgenus Sarcodexia was monophyletic and supported by two character states, one of them is the abruptly smaller male genitalic segments with regard to the size of the abdominal segments. Roback (1954) stated that the phallus of Sarcodexia has no vesica, but we observed a small, round, sclerotized plate arising from the anterior surface near the base of distiphallus (Figs. 3g and 5e), which is in agreement with the definition of vesica of Giroux et al. (2010).

The monophyly of Squamatodes was supported by one uniquely derived apomorphy: lateral styli fused (Fig. 3d, also see description in Buenaventura and Pape 2013).

Pape (1996) transferred Blaesoxipha (Gigantotheca) virgo ( Pape 1994) to Peckia and placed it in the subgenus Euboettcheria due to the presence in this species of a mid femoral ctenidium. Later, Buenaventura and Pape (2013) transferred B. (Gigantotheca) virgo to Squamatodes . We found no support for considering this species as part of the subgenus Euboettcheria . In the present analyses, P. (Squamatodes) virgo emerged as the sister taxon of the clade ( P. (Squamatodes) ingens + Peckia (Squamatodes) trivittata ). These three species make up the subgenus Squamatodes , which lack a vesica and possess fused lateral styli.

Figures

Fig. 8 Majority-rule (50 %) consensus tree from the BI analysis of the morphological data using the third character-coding scheme for the acrophallus

Fig. 9 Phylogenetic tree from the BI analysis of the molecular dataset

Fig. 4 Engelimyia inops. Distiphallus left lateral view, lateral stylus highlighted in orange. ca capitis, h harpes, j juxta, ls lateral stylus, mp median process, pp paraphallus, slp stylar lateral plate, sml stylar membranose lobe, v vesica. Scale bar 100 μm

Fig. 5 Juxtal configuration in the subgenera of Peckia, left lateral view, juxta highlighted in green. a Peckia (Pattonella) intermutans. b Peckia (Squamatodes) ingens. c Peckia (Euboettcheria) naides. d Peckia

Fig. 10 Evolution of juxta. Majority-rule (50 %) consensus tree from the BI analysis of the morphological data using the third character-coding scheme for the acrophallus, with branches of genera and subgenera of the Peckia clade collapsed. Insets of an exemplar phallus for each terminal taxon, juxta highlighted in green

Fig. 6 Juxtal character states in three of the subgenera of the genus Peckia. a Subgenus Euboettcheria. Juxta entire with arrows showing a juxta expanded uniformly along its entire distal margin. b Peckia (s. str.). Juxta with juxtal lateral plates each with a basal and a distal horn. c Sarcodexia. Juxta with juxtal lateral plates each with a basal and two distal horns. bjh basal juxtal horn, djh distal juxtal horn, j juxta, jlp juxtal lateral plate

Fig. 7 Juxtal configuration in the subgenus Sarcodexia, posterior view, dashed line showing point of origin of the juxta. a Peckia (Sarcodexia) notata. b Peckia (Sarcodexia) lambens. c Peckia (Sarcodexia)

Fig. 12 Abdominal tergites 1+2–5, outline in left lateral view. a Peckia (Pattonella) intermutans. b Peckia (Squamatodes) ingens. T abdominal tergites

Fig. 13 Peckia (Pattonella) kladosoides. Distiphallus, left lateral view, arrow showing point of attachment of vesica. lsv long segment of vesica, ssv short segment of vesica