Pilophorus boninanus, Polhemus & Yasunaga, 2021

Polhemus, Dan A. & Yasunaga, Tomohide, 2021, A new species of the plant bug genus Pilophorus Hahn from the Ogasawara (Bonin) Islands, Japan (Hemiptera: Heteroptera: Miridae: Phylinae), Zootaxa 5060 (3), pp. 447-450 : 447-450

Pilophorus boninanus n. sp.

( Figs. 1A–D , 2A–B )

Pilophorus perplexus: Carvalho, 1956: 70 (faunal list) (non Douglas & Scott, 1875).

Pilophorus setulosus: Schuh, 1984: 126 (diag.) (non Horváth, 1905; cf. Yasunaga et al., 2021).

Type material. Holotype (♂). JAPAN: Bonin ( Ogasawara ) Islands , Chiohi Jima [misspelling of ‘Chichi’ Jima ], Sakai Ura [27°05’11”N 142°12’27”E], 4 Jul 1949, A. R. Mead [with two det. labels: Pilophorus perplexus (H.S.) / JCM Carvalho , 1954 and P. setulosus Horvath / R. T. Schuh , 1982] ( BPBM) ( AMNH _ PBI 00380692 ) . Paratype. JAPAN: Bonin Islands, Ani Jima, north end [27°08’33”N 142°11’31”E], 11 Jul 1949, A. R. Mead, 1 ♀ ( BPBM) (00380693).

Diagnosis. Recognized by its rather ovoid, weakly ant-mimetic body that is not strongly constricted at the middle; sparsely distributed, dark, semierect setae on the dorsum; somewhat clavate antennal segment II; brown hemelytra with a continuous median band of scale-like setae; weakly splayed-out left paramere with rather elongate hypophysis ( Fig. 2A ); and slender, J-shaped vesica with a small, bifurcate median process ( Fig. 2B ). This new species is most similar in general appearance to P. miyamotoi Linnavuori ( Fig. 1E ), from which P. boninanus can be distinguished by the following characters: vertex wider [versus less than 0.6 mm in miyamotoi ]; anterior half of scutellar margin with silvery setae [versus anterior 1/3 with clustered silvery setae]; short anterior band of silvery setae at an angle of 55° to claval commissure ( Fig. 1A ) [versus 30–35° ( Fig. 1E )]; left paramere cup-shaped, with elongate hypophysis ( Fig. 2A ) [versus splayed-out with short hypophysis ( Fig. 2C )]; and vesical bifurcate median process smaller, situated rather basally ( Fig. 2B ) [versus broader and situated at apical 1/3 ( Fig. 2D )].

Description. Macropterous male: Overall length 3.90, length from apex of head to cuneal fracture 3.00, maximum width (across base of cuneus) 1.55. General coloration dark brown, with clavus and majority of corium yellowish-brown ( Figs. 1A, C ).

Head: Length 0.35, width across eyes 1.10, dark brown; eyes dark red, length 0.45, width 0.45; vertex width 0.75; frons and vertex shining, bearing scattered, semi-recumbent, short golden setae. Antennae with segment I yellowishbrown, segment II medium brown basally intergrading to dark brown distally, segment III pale yellow, segment IV missing; segment I bearing 3 erect spinose golden setae, all segments thickly covered with short, stiff, semi-erect goldenbrown setae; lengths of segments I–IV: 0.30, 1.30, 0.45, missing. Labium length 1.60, reaching to between middle coxae and hind coxae, entirely shining reddish-brown.

Thorax: Pronotum length 0.60, width 1.25, weakly campanulate, uniformly dark brown, surface shining, bearing scattered short, semi-recumbent, simple golden setae. Scutellum length 0.75, width 0.85, uniformly dark brown, mesoscutum transversely tumid, central scutellum weakly raised; surface bearing scattered short, semi-erect, golden, simple setae plus 3 small patches of dense, recumbent silvery setae, two of these lying basally at anterolateral angles of scutellum adjoining mesoscutum, the third extending as a narrow transverse band immediately anterior to scutellar apex. Hemelytra with clavus, inner two-thirds of corium, and inner corium on posterior third dull yellowish-brown, outer corium on posterior third and adjacent cuneus shining dark brown; hemelytral surface bearing scattered, moderately short, recumbent, posteriorly-directed, spine-like, reddish-brown setae; corium with narrow transverse band of short, dense, silvery setae at one-third distance from basal angle, a second similarly narrow silvery band present at approximately two-thirds distance from basal angle, the latter (median) band also extending transversely across subapical portion of clavus; diffusely scattered silvery setae also present at inner angle of cuneus and along adjacent posterior margin of corium. Legs uniformly reddish-brown, all segments clothed with very short, recumbent, gold setae; all tibiae bearing erect, dark brown spines, lengths of these spines not exceeding the width of the respective tibia on which they occur. Ventral surface: Pale shining reddish-brown, ostiolar peritreme prominent, dull yellowish-brown, abdomen missing.

Genitalia ( Fig. 2A–B ): Left paramere cup-shaped, with blunt, broadly rounded basal lobe (sensory lobe) and slender, tapering distal process (hypophysis) tapering to slight hook apically ( Fig. 2 ). Structures of J-shaped vesica as shown in Fig. 2B (not removed from phallotheca); median process small, bifurcate.

Macropterous female: Overall length 3.90, length from tip of tylus to cuneal fracture 3.00, maximum width (across base of cuneus) 1.50; similar to male in general structure and coloration ( Figs. 1C–D ), with following exceptions: ventral abdomen shining blackish brown, with ovipositor sheath extending 0.65 its length posteromedially.

Etymology. Named for the Bonin ( Ogasawara ) Islands, the type locality of this new species.

Distribution. Japan: Ani-Jima and Chichi Jima in the Ogasawara (Bonin) Islands.

Discussion. The Ogasawara Islands (also referred to as the Bonin Islands) are a set of subtropical oceanic islands known to harbor a unique fauna and flora, with a number of endemic organisms (cf. Ministry of the Environment Government of Japan, 2007 –2011; UNESCO World Heritage Centre, 1992 –2001). More than ten heteropterans are regarded to be endemic to the island-group, whereas some introduced bugs (predaceous species in particular) threaten the indigenous species ( Yasunaga, 1995, 2000, 2001; Yasunaga et al., 1993). Currently, the following sixteen species of the Miridae are known to inhabit the Ogasawara Islands [*considered endemic; †NT: Near Threatened rank in the official Red List of Japanese Ministry of Environment]: Fulvius anthocoroides (Reuter, 1875) , Campylomma boharti Carvalho, 1956 *, C. boninensis Carvalho, 1956 *, C. livida Reuter, 1885 , Moissonia punctata (Fieber, 1861) , Tytthus chinensis (Stål, 1860) , Pilophorus boninanus n. sp. *, Sthenaridea piceonigra (Motschulsky, 1863) , S. rufescens (Poppius, 1915) , Anthophilolygus bakeri (Poppius, 1915) , Creontiades brevis Yasunaga, 1997 *, C. coloripes Hsiao, 1963 , Lygocorias boninensis (Yasunaga, 1992) *†, Paurolygus sp. (Schwartz & Yasunaga, unpublished data), Taylorilygus apicalis (Fieber, 1861) and Trigonotylus tenuis Reuter, 1893 .

Our pair of specimens of Pilophorus from this archipelago were previously recorded as P. perplexus by Carvalho (1956) and P. setulosus ( Fig. 1F , 2F–G ) by Schuh (1984), both of which are predominantly associated with deciduous broadleaf trees in temperate or cold temperate climatic zones (cf. Schuh & Schwartz, 1988; Yasunaga, 2001). Some subsequent works ( Yasunaga, 2001; Yasunaga & Duwal, 2016; Yasunaga et al., 2021) doubted the occurrence of such species on these isolated subtropical islands.

The present new species was also suspected to have been introduced to the islands from another part of Japan or the Nearctic Region (as Ogasawara was administered by the United States after World War II from 1945 to 1978). However, the present examination of the male genitalia verifies that Pilophorus boninanus n. sp. does not match any other congeners known from Japan and adjacent regions. In addition, no Nearctic Pilophorus species is conspecific with it, based on the diagnostic characters including the male genitalia and in the key to the New World Pilophorus congeners provided by Schuh & Schwartz (1988).

In the key to Japanese Pilophorus species ( Yasunaga et al., 2021), the specimens from the Ogasawara Islands will key out to P. miyamotoi Linnavuori , but P. boninanus n. sp. can be distinguished by the characters mentioned in above diagnosis. The current preponderance of evidence suggests that P. boninanus n. sp. is endemic to Ogasawara Islands , although further field investigation is encouraged to acquire additional specimens and biological data that will allow clarification of its plausible phylogenetic position.

Figures

FIGURE 1. Habitus images of Pilophorus spp. A. P. boninanus, holotype male, dorsal view (AMNH_PBI 00380692). B. Same, left lateral view (abdomen removed for dissection). C. Same, paratype female (00380693). D. Same, lateral view. E. P. miyamotoi, male (from Hokkaido, Japan). F. P. setulosus, female (Hokkaido).

FIGURE 2. Male genitalia of Japanese Pilophorus spp. A−B. P. boninanus, holotype (AMNH_PBI 00380692). C−E. Same, P. miyamotoi (from Shikoku, Japan). F−G. P. setulosus, female (Hokkaido). A & C. Left paramere. B. Phallotheca + vesica (endosoma). E & G. Vesica. D & F. Phallotheca.