Discovery of a New World ladybird beetle Nephaspis indus Gordon, 1996 (Coleoptera: Coccinellidae: Scymnini) on the Island of Taiwan

Abstract Background Nephaspis indus Gordon, 1996 was imported into Taiwan from Hawaii in 1990 as a biological control agent for the spiralling whitefly, Aleurodicus dispersus Russell, 1965 (Hemiptera: Aleyrodidae). However, its establishment was not known prior to this study. New information Nephaspis indus Gordon, 1996, a natural enemy of Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae) native to the Neotropical region, is recorded as established in Taiwan for the first time. The present paper provides a detailed further description and illustrations of the adult. Diagnostic characters for the genus and species are given and the nomenclature of this species is also discussed.


Introduction
Nephaspis Casey, 1899 (Coleoptera: Coccinellidae: Scymnini) is a New World genus and currently includes 43 species distributed from southern United States to Argentina (Gordon 1996 ). This genus was initially described by Casey (1899) based on two species, N. gorhami and N. brunnea from Central America. Later, he placed N. brunnea as a synonym of N. gorhami (Casey 1905). Wingo (1952) described another species, N. amnicola from North America. However Gordon (1985) synonymised this species with N. oculatus (Blatchley) which was transferred from Scymnus to Nephaspis, based on the examination of their holotype. Nephaspis was first revised by Gordon (1972) who described an additional species N. cocois from Brazil and also recognised that the Guyana species Clitostethus dispar Sicard, 1929(Sicard 1929 is congeneric. Subsequently, Gordon (1978Gordon ( , 1982Gordon ( , 1990 described five species from Trinidad, Colombia, Argentina and Puerto Rico and Duverger (1986) described one more species from Nicaragua. In his comprehensive revision of the genus Nephaspis, Gordon (1996) recognised and described 32 more species to this genus from South America, transferred Scymnus convexus Nunenmacher, 1937 to Nephaspis and provided a detailed description of this species.
Members of the genus Nephaspis are predators of whiteflies (Hemiptera: Aleyrodidae) (Gordon 1996). In 1988, the spiralling whitefly, Aleurodicus dispersus Russell, 1965 which is native to the Central America and Caribbean regions, was discovered in southern Taiwan and soon became a serious pest for fruit trees, vegetables, food crops, shade trees and landscape ornamentals (Chien et al. 2002). Due to the wide range and scattered distribution of its host plant and the difficulty with insecticide spraying on tall trees, biological agents were sought to control this invasive pest. Therefore, Nephaspis indus Gordon was imported into Taiwan from Hawaii in 1990 with a view to controlling the spiralling whitefly, Aleurodicus dispersus (Wen 1995). However, it is uncertain whether it was established at that time (Chien et al. 2002, Yu 2011.
In this paper, Nephaspis indus Gordon, 1996 is recorded as being established in Taiwan for the first time. The detailed further description and illustrations of the adult are provided. Diagnostic characters for the genus and species are given and the nomenclature of this species is also discussed.

Materials and methods
Specimens examined were collected from the Island of Taiwan and deposited in the Department of Entomology, South China Agricultural University, Guangzhou, China (SCAU). The morphological terms follow Ślipiński (2007) and Ślipiński and Tomaszewska (2010).
Measurements were taken using a micrometer attached to a SteREO Discovery V20 dissecting stereoscope and are defined as follows: (TW) total width, across both elytra at widest part; (TH) total height, at highest part of elytra in lateral view; (TL) total length, from apical margin of clypeus to apex of elytra; (PL) pronotal length, from the middle of anterior margin to the base of pronotum; (PW) pronotal width at widest part; (EW) elytral width, equal to TW; (EL) elytral length, along suture from base to apex including scutellum; (HW) head width, at widest part including eyes.
Male and female genitalia were dissected, cleared in a 10% solution of NaOH by boiling for several minutes and placed on slides for further study. Photographs of the whole beetles and their genitalia were taken using digital cameras (AxioCamHRc and Coolsnap-Procf& CRI Micro*Color) attached to the microscope. The final plates were laid out with Adobe Photoshop CS 8.0. Nephasis : Korschefsky 1931: 168;Blackwelder 1945: 445 (misspelling).

Description
Body elongate oval, moderately convex, with dense pubescence, widest around middle of elytra.

Distribution
This genus is apparently endemic to Neotropical region with a natural geographic range extending from southern United States (Florida, Louisiana and Texas) and Mexico to Argentina (Gordon 1996). In addition, several species of this genus are specialist predators of the spiralling whitefly, Aleurodicus dispersus. As important biological control agents against the spiralling whitefly, these members of Nephaspis have been introduced into different parts of the world, such as Hawaii, Guam, Fiji, Taiwan and Thailand (Waterhouse and Norris 1989, Chien et al. 2002, Napompeth 2004).
Male genitalia. Penis long, strongly curved at basal 1/2 length (Fig. 2h); penis capsule with long inner arm and short outer arm; apex of penis with membranous appendage (  Fig. 2i). Tegmen stout ( Fig. 2j-k) with penis guide widest at base, tapering gradually to pointed apex in ventral view (Fig. 2j) and its base with prominent dorsal keel in lateral view (Fig. 2k). Parameres tapering toward apex, as long as 2/3 length of penis guide, covered with several long setae at apices (Fig. 2k).

Diagnosis
This species is similar to Nephaspis bicolor Gordon, 1982 in general appearance, but can be distinguished from the latter by details of male genitalia, particularly the stout penis guide with a dorsal keel at basal 1/3 length in lateral view (Fig. 2k) and the black pronotum with yellow anterolateral angles in female (Fig. 2e). In N. bicolor, the penis guide with a high dorsal keel at basal half in lateral view and the yellow pronotum with median 1/3 dark brown in female (Gordon 1996).

Notes
There was some confusion about the taxonomy and nomenclature of N. indus. This species was introduced from Honduras, Trinidad and the West Indies into Hawaii as N. amnicola in 1979-1980 where it became effective in biological control of the spiralling whitefly (Kumashiro et al. 1983). A few years later, Gordon (1996) described a new species, N. indus, based on the specimens from Hawaii. Actually, this is a Trinidadian species, although the type series were all from Hawaii. He also pointed out that the male genitalia figured in Gordon (1982) for N. bicolor are those of N. indus, because a male of the latter species was mixed in with the type series of N. bicolor and that was the specimen selected for illustration (Gordon 1996).