First record of the family Issidae (Hemiptera, Auchenorrhyncha, Fulgoroidea) from the Hawaiian Islands

Abstract Background Euroxenusvayssieresi (Bonfils, Attie & Reynaud, 2001) (Issinae, Sarimini) was described (in the genus Borbonissus Bonfils, Attie & Reynaud, 2001) from Réunion Island, in the Indian Ocean and, previous to this report, has not been recorded elsewhere. Euroxenusvayssieresi is here illustrated and re-described to improved taxonomic diagnosis. New information Euroxenusvayssieresi is recorded for the first time from the Island of Hawaii in the Hawaiian Archipelago. This is first record of the family Issidae from the Hawaiian Archipelago.


Introduction
The Hawaiian planthopper (Hemiptera, Auchenorrhyncha, Fulgoroidea) fauna consists of 207 endemic species (64 Cixiidae plus 143 Delphacidae) and at least 15 adventive species (10 Delphacidae, 2 Flatidae, 1 Tropiduchidae and 2 Derbidae) (Zimmerman 1948, Beardsley 1979, Beardsley 1990, Asche 1997, Asche 2000a, Asche 2000b, Nishida 2002, Hoch 2006. No additional adventive planthopper species have been reported since the publication of the Fourth Edition of Bishop Museum's Hawaiian Terrestrial Arthropod Checklist (Nishida 2002), i.e. Matsunaga et al. (2019). Beardsley (1979) reported that the rate of 'accidental immigration and establishment' was about 16 species a year between 1937 and 1961 and about 19 species a year between 1962 and 1976 (subsequent rates have not been reported). The importation of live plant material may be the main source of immigrant species (at least for phytophagous insects) (Beardsley 1979, DeNitto et al. 2015, Mound et al. 2017) and the primary sources of introductions are the mainland, the United States and Asia-Pacific (DeNitto et al. 2015). Here, we report an established species of Issidae, found at three localities on the western side of the Island of Hawaii in 2021.
The planthopper family Issidae comprises about 1,090 species in 217 genera distributed worldwide (Bourgoin 2021). Issids are absent in southern Africa (except for two species of the genus Ikonza Hesse, 1925 from north Namibia and south Angola), Madagascar, the Seychelles and Tasmania , Gnezdilov 2016. In Oceania, Issidae are known from New Guinea (eight genera, 17 species), the Solomon Islands (one species) and Fiji (one species) , Gnezdilov 2020b), but are absent in Micronesia and Polynesia including New Zealand and Hawaii. In the South Indian Ocean, the Issidae are known only from the Mascarene Archipelago (two species, Bonfils et al. 2001), consisting (in part) of the large islands Mauritius, Réunion and Rodrigues.  (Gnezdilov 2009). Gnezdilov (2009) postulated that the issid fauna of Réunion Island had an Oriental genesis and proposed a close relationship of Euroxenus and the Oriental genus Eusarima , recently supported by molecular data (Gnezdilov et al. in press). Thabena brunnifrons was later recorded from Rodrigues, Taiwan, Dongsha (Pratas) Islands and Singapore (Chan et al. 2013, Gnezdilov 2014b. Here, we record E. vayssieresi from the Island of Hawaii in the Hawaiian Archipelago. This species is re-described to improve on diagnostic features reported by Gnezdilov (2009) and Gnezdilov (2020).

Materials and methods
Morphological terminology follows Anufriev and Emeljanov (1988) and . Photographs were taken using a Canon EOS 5D Mark IV camera with the lens Canon-MP-E-65mm f/2,8 1-5x Macro and the flash Canon Macro Twin-Lite MT-26EX-RT. Images were produced using Helicon Focus v. 7.6.4 and Adobe Photoshop СС 2019 software. The genital segments of male specimens examined were macerated in 10% potassium hydroxide (KOH) and figured in glycerine jelly (Brunel Micro Ltd, UK) using a Leica MZ9.5 stereomicroscope with a camera lucida. The map was prepared using Google Earth Pro (version 7.3) with map data sources as attributed in image.     Structure. Body length, males and females -4.0 mm. Metope (~ frons, Fig. 3) broad, widest below the eyes, with distinct median carina running from upper margin through postclypeus; sublateral carinae distinct, joined with median carina at metopial upper margin (carinae somewhat projecting along upper margin), almost reaching metopoclypeal suture. Postclypeus broadly rhomboid. Rostrum reaching hind coxae, 2 and 3 segments are almost equal in length; 3 one narrowing apically. Antennal scape very short, pedicel globular, just longer than wide. Coryphe (~ vertex , Figs 1, 4) as concave hexagon, slightly wider than long medially, anterior margin produced, obtusely angled, posterior margin concave. Metope and coryphe (in lateral view, Fig. 2) joined at obtuse angle (dorsal portion of sublateral carinae somewhat projecting). Ocelli vestigial. Eyes large, each eye nearly as wide as coryphe.
Hind wing with coupling lobe and deep cubital and vannal clefts (Fig. 5); anal lobe less wide than remigial and remigio-vannal lobes. Hind wing vein sequence: R 2, furcating apically after coupling lobe; r-m 1; M 1; m-cua 1; CuA 2; CuP 1; Pcu 1; A 2; A 1. CuA and CuP fused and flattened apically and Pcu and A fused medially. Front and middle femora slightly flattened. Hind tibia with two large lateral spines past mid-length and six apical spines. First and second metataromeres of subequal length, but basitarsus wider; basitarsus with two latero-apical spines and 13 intermediate spines arranged in arc; ventral surface with long setae; second metatarsomere with pair of latero-apical spines and median lobe.
Male terminalia: Pygofer (in lateral view, Fig. 6A) elongate vertically, with convex hind margins. Hind margin of sternite VII straight (ventral view). Phallobase ( Fig. 6B and C) narrow and strongly curved (in lateral view), with a narrow process dorsally (Fig. 6B dp  ); each dorsolateral phallobase lobe with three-branched large process -two branches directed dorsally and the longest branch directed basally, with serrulate carina. Each dorsolateral phallobase lobe (in lateral view) with a lateral slit and folds near middle and with narrow semicircular subapical lobe. Ventral phallobase lobe long and wide, with an apical notch. Aedeagus with a pair of long (0.3× length of phallobase, Fig. 6B and C), narrow, apically pointed ventral hooks, arising subapically and directed basally. Apical aedeagal processes long and wide apically (Fig. 6B, shaded). Gonostylus (Fig. 6  E) with deeply concave hind margin. Capitulum wide, not narrowing apically (in dorsal view, Fig. 6F), with small lateral tooth (in lateral view). Connective (lateral view, Fig. 6B) with small cup and long handle, in caudal view (Fig. 6G), with ventral margin bilobed (these articulating with the gonostyli). Anal tube elongate (Fig. 6A), in dorsal view ( 6D) nearly 3 times as long as wide medially, slightly narrowing apically, with weak apical concavity. Anal column 0.3x as long as anal tube, narrow.
Notes: Gnezdilov (2020) (in fig. 2) had not observed a small basal process of threebranched processes of dorsolateral phallobase lobes ( Fig. 6B and C) on his drawings of male genitalia of E. vayssieresi from Réunion Island (Saint-Paul); otherwise no significant differences in external morphological features were found between the specimens from Réunion (La Possession and Saint-Paul) and those of the Hawaii Islands.

Discussion
The specimens of Euroxenus vayssieresi were all collected in 2021 in very dry areas, on the west side of the Island of Hawaii at three localities (Fig. 7 al. (2001) noted that their specimens were collected in semi-dry secondary vegetation on exotic and native plants located on the northwest and west of the "leeward" region of Réunion, which is similar to the circumstances where this species was found in Hawaii.
Issids are not typically good dispersers (many are sub-brachypterous and flightless) and transport of Euroxenus vayssieresi to Hawaii is most likely by human agency and in association with live plants. This was previously hypothesised as the mode of transport for other issid species O'Brien 2006, Gnezdilov 2009). Collecting localities for Euroxenus vayssieresi on the Island of Hawaii (black circles). Map created using Google Earth, map data sources provided in the lower left of the image.