Calistocoris Reuter, 1881

Swanson, Daniel R., 2019, Doomed to a vile lot: new taxa, notes, and an updated generic key for the Old World corsairs (Heteroptera: Reduviidae: Peiratinae), Zootaxa 4700 (2), pp. 196-228 : 201-202

Calistocoris Reuter, 1881

( Figs. 4, 5 )

Calistocoris Reuter, 1881: 318 . Type species: Calistocoris caesareus Reuter, 1881 ; by monotypy.

Polychitonocoris Miller, 1940: 597 . Type species: Polychitonocoris formosus Miller, 1940 ; by original designation. Synonymized by Coscarón, 2002: 27.

Reuter (1881) described the monotypic genus Calistocoris with a single species, C. caesareus , from Borneo. Fiftynine years later, Miller (1940) described the new genus Polychitonocoris for two new Malaysian species: Polychitonocoris formosus Miller, 1940 from Sarawak and Polychitonocoris virgo Miller, 1940 from Pahang. All three species remained unmentioned in the literature, other than in the two global catalogs ( Putshkov & Putshkov 1985, 1987; Maldonado Capriles 1990), until Coscarón (2002) redescribed the taxa, correctly synonymizing P. formosus with C. caesareus .

As Coscarón (2002) did not include much comparative justification, I offer my own independent observations: It is unsurprising that Miller (1940) did not make any comparisons in his original description between Polychitonocoris and any other peiratine genus, as the slender form of the head and pronotum is unique among peiratine assassin bugs. However, Calistocoris also possesses this feature, as was indicated in Reuter’s (1881) description: “[Pronotum] lobo antico angustulo, antice convexo”. Other morphological details shared by these two taxa are summarized in Table 1 ; each character state individually is not unique to the taxa, but when grouped, they all strengthen the case for conspecificity. Biogeographical evidence further supports this synonymy. Reuter’s species was described from “Borneo (Matang)”, and Miller’s type species was described from “ Sarawak, Mt. Matang”, with a paratype from Mt. Selinguid. Thus, it appears that Miller’s type species, P. formosus , is geographically syntopic with C. caesareus . The second of Miller’s species, P. virgo , comes from “ Pahang, F.M.S., Kuala Teku”. The distributional details are summarized in Fig. 6 (but see note under Materials & Methods: Biogeography). The obvious similarities and biogeographical proximity with Calistocoris would have required comparison with Polychitonocoris ; thus, I have speculated that Miller must have been unaware of Reuter’s genus, despite it being present in an important and unobscure treatise on Old World Reduviidae .

When originally confirming my suspicion that P. formosus was a junior synonym of C. caesareus , I requested photographs of the male holotype of Polychitonocoris formosus ( Fig. 4 ) and the female holotype of Polychitonocoris virgo ( Fig. 5 ). I also requested images of the female holotype of Calistocoris caesareus from HNHM, although I have been informed that the type was borrowed 22 years ago, and despite multiple requests, has not yet been returned (Rédei, pers. comm. 2017). Similarly, the female paratype of Polychitonocoris formosus purportedly deposited in SMSM is neither in that institution (Leh, pers. comm. 2017) nor in BMNH (Webb, pers. comm. 2017). Thus, the type of C. caesareus remains inaccessible, and I am unable to corroborate the synonymy as rigorously as is preferable. Nevertheless, the details discussed above strengthen the case, leaving the synonymy satisfactory until the holotype can once again be examined.

The following key will enable separation of the species:

Figures

FIGURE 6. Generalized type localities of Calistocoris caesareus, Polychitonocoris formosus, and Polychitonocoris virgo. HT = holotype, PT = paratype.

FIGURES 4–5. Dorsal habitus: (4) male holotype of Polychitonocoris formosus (BMNH); (5) female holotype of Polychitonocoris virgo (BMNH). Both images taken by Keita Matsumoto, ©Natural History Museum, London. Scale bar =2 mm.

Tables

TABLE 1. Similarity in language in the original description of various morphological conditions possessed by Calistocoris caesareus and Polychitonocoris.

Calistocoris caesareus (in Reuter 1881)	Polychitonocoris (in Miller 1940)
“capite...postice fortes constricto… parte ante-oculari posto-	“Head…strongly constricted basally… anteocular a little
culari longiore” “clypeo leviter elevato”	longer…than postocular” “clypeus somewhat elevated in front of antennae”
“rostro…articulo secundo primo duplo fere longiore”	“rostrum…segment 2 about twice as long as basal segment”
“antennis…articulis secundo et tertio fere aeque longis”	“Antennae…segment 2, 3.50 mm.; segment 3, 3.30 mm ”
“pronoto apice truncate, angulis apicalibus sub-rectis… lobo	“Anterior lateral margins of pronotum feebly produced…
antico angustulo, antice convexo, lateribus subcompresso” “scutello parum producto, apice levius recurvo”	anterior lobe sub-elliptical” “Scutellum with a short projection apically”
“pronoto, scutello…sat dense granulatis”	“anterior lobe granulose…posterior lobe granulose…Scutel-
“mesosterno carinato”	lum…with scattered granules” “Meso- and metasterna with a median carina”
“anterioribus fossa spongiosa instructis, hac fossa fere ¾	“spongy area on anterior and median tibiae more than half
tibiarum anticarum” “clavo, corio intus…sordide ochraceis”	the length of tibia” “Corium rufo-ochreous; clavus and median area ochreous”