Endemics Versus Newcomers: The Ladybird Beetle (Coleoptera: Coccinellidae) Fauna of Gran Canaria

Simple Summary Many plants and animals that live in the Canary Islands belong to the so-called endemic species, i.e., they do not occur outside of this particular region. Several other species have a slightly wider geographical distribution, apart from the Canaries, which also includes some islands of the nearby archipelagos, such as Madeira or the Azores, or the northwestern periphery of Africa. Here, we call such species subendemics. However, the Canary Islands have recently been colonized by a substantial number of immigrants from more or less remote areas. In this paper, based on our field survey and previously published data, we analyzed the fauna of the ladybird beetles (Coccinellidae) of Gran Canaria, one of the central islands of the archipelago. Among 42 ladybird beetle species so far recorded on this island, 17 (40%) are endemics and subendemics, and 21 (50%) probably arrived in Gran Canaria relatively recently, i.e., in the 20th and 21st century. Of those newcomers, there are Australian, American, African, and European species. The nonnative ladybird species may pose a threat to the unique ladybird communities from Gran Canaria and other islands of the archipelago. Abstract Research on the fauna of beetles (Coleoptera) of the Canary Islands has a long tradition, which enables tracking changes in their species composition and arrival of new species. In this paper, we provide new faunistic data on the ladybird beetles (Coccinellidae) recorded on Gran Canaria, one of the central islands of the archipelago, and then analyze available information on the Gran Canarian ladybird fauna from geographical and historical points of view. The field survey resulted in recording 1402 ladybird individuals belonging to 30 species. Ten of these species were new to Gran Canaria and three of them, Chilocorus bipustulatus (Linnaeus), Nephus bisignatus (Boheman), and Nephus ulbrichi Fürsch, had not previously been reported to be on any of the islands of the Canarian archipelago. Tetrabrachys tinerfensis (Hodgson) is synonymized with T. deserticola (Wollaston). Our survey and literature reports allowed us to recognize 42 species of Coccinellidae so far recorded on Gran Canaria. Seventeen of them (40%) belonged to the Canarian endemic and subendemic species, and 21 (50%) were newcomers and presumed newcomers. Colonization of Gran Canaria and other islands of the archipelago by ladybird species of various origins seems to be a frequent phenomenon that may pose a threat to the unique communities of the native Canarian species.


Introduction
A substantial portion of the Canarian biodiversity is composed of endemic species. For example, the endemism rate among the terrestrial arthropods is estimated to be around 38% [1,2]. The subject of our study, the Coleopteran family Coccinellidae, has about 50 recorded species in the Canaries [3][4][5], and 14 of them (28%) are considered to be endemic species [3]. However, many of the Canarian ladybirds have only recently arrived on the archipelago. Several such species were listed by Oromí et al. [3] and the next two were added by Suárez et al. [5] and Romanowski et al. [4].
The first published data on the Coccinellidae of the Canary Islands came from the early 19th century [6][7][8]. Then, significant contributions to the knowledge of the Canarian ladybirds were made by Wollaston [9,10], Uyttenboogaart [11,12], Korschefsky [13], Lindberg [14], and Fürsch [15]. More recently, further reports were provided by various authors, and the available data were summarized by Machado and Oromí [16], Eizaguirre [17], and Oromí et al. [3]. Despite this long history of studying ladybird fauna in the Canary Islands, the species composition on individual islands has not been sufficiently documented. Our recent surveys on Fuerteventura [4,18], Lanzarote [19], and El Hierro [20] allowed us to record many ladybird species not previously reported to be on those islands.
This paper concerns the Coccinellidae on another island of the archipelago, Gran Canaria. First, we provide new faunistic data, and then analyze available information on the Gran Canarian ladybird fauna from the geographical (distributional patterns) and historical (dates of records) points of view.

Study Area, Materials, and Methods
The Canary Islands lie in the northeast Atlantic Ocean near the African coast and are comprised of seven main islands and several islets. High biodiversity combined with diversification of the islands with respect to the size, age, landforms, and distance from the continent [1,2] make the archipelago an excellent system for biogeographical analyses.
Gran Canaria is one of the central islands of the Canarian archipelago, located some 200 km from the African mainland. It was formed about 14.5 million years ago as a result of volcanic eruptions [2]. Of nearly circular shape, the island is elevated to 1950 m a.s.l. at its highest point (Pico de las Nieves) [21]. The vegetation of Gran Canaria includes a wide range of habitats, such as coastal dunes, scrub vegetation with Euphorbia spp., or pine forests with Pinus canariensis D. Smith. In anthropogenic habitats, decorative plants sustained by irrigation are cultivated ( Figure 1).

Faunistic Survey
Ladybirds were recorded at 55 sites on Gran Canaria (Table 1) using standard collecting methods, such as beating tray, sweeping net, or direct observation. Although some of the caught ladybird individuals were released after their identification, each individual was noted. The majority of specimens were recorded by J. Romanowski and P. Ceryngier between 31 March and 6 April 2019. Some material collected earlier in 2001, 2015, 2016, and 2017 by F. Pavel, J. Krátký, and M. Piotrowska, was also used in this study. In the result section, we mention names of the collectors if they are different from J. Romanowski and P. Ceryngier. The voucher specimens are stored in the insect collection in the Institute of Biological Sciences, Cardinal Stefan Wyszyński University in Warsaw and in private collections of Jaroslav Větrovec (materials collected by F. Pavel and J. Krátký) and Marta Piotrowska. Unless specifically discussed, the nomenclature of Coccinellidae follows Kovář [22], and systematic arrangement followsŚlipiński [23] and Seago et al. [24].

Geographical and Historical Analysis of the Ladybird Fauna on Gran Canaria
On the basis of the literature data and results of this study, we compiled a list of all ladybird species recorded on Gran Canaria. Records of these species, both on Gran Canaria and other islands of the Canary archipelago, were allocated among the following three time periods: (1) 19th century (primarily the classical Wollaston's [9,10] works); (2) first half of the 20th century (important contributions from Uyttenboogaart [11,12,25] and Lindberg [14], and several other reports); and (3) records after 1950.
Next, according to this historical arrangement of records and available data on the general distribution of the species recorded on Gran Canaria, we assigned each species to one of six groups within the following two rough categories: (1) endemic and subendemic species and (2) species with wider ranges. In the first category, we distinguished species endemic to Gran Canaria, species endemic to the Canary archipelago, and subendemic species. The latter category included species known both from the Canary Islands and some other islands of Macaronesia or from the Canary Islands and northwestern Africa. Among the species with wider ranges, we distinguished a group of non-endemic old inhabitants of the archipelago, presumed newcomers and alien species. According to our classification, the old inhabitants were widely distributed taxa already recorded in the Canary Islands in the 19th century. The presumed newcomers were not recorded in this period and, hence, probably arrived on the archipelago relatively recently. This group consisted of species that had spread naturally from the Mediterranean region, Africa, or other islands of Macaronesia, as well as those whose arrival in the Canary Islands associated with human activities such as trade. The last group (alien species) consisted of species coming from remote places in the world. They certainly or almost certainly arrived in the Canary Islands through the mediation of man.

Faunistic Survey
Altogether, 1402 ladybird individuals (1327 adults, 72 larvae, and 3 pupae) belonging to 30 species were recorded in this study. Distribution: Native to North America but used outside of its native range as a biocontrol agent against whiteflies (Hemiptera: Aleyrodidae) [26]. Recorded on most of the islands of the Canarian archipelago, i.e., La Palma [27], La Gomera [17], Tenerife [17,28], Fuerteventura [18], and Lanzarote [19]. New to Gran Canaria. Distribution: Endemic Gran Canarian species, until this study, only reported from the surroundings of Maspalomas [9,29] and Las Palmas [10,11]. Tufia, on the eastern coast of the island, is the third known locality of this species. Distribution: Widely distributed in the Mediterranean and Middle East countries, as well as in northwestern India, Pakistan and the Afrotropical region [22,30]. Known to be on all islands of the Canary archipelago except La Palma [3,17].
Remarks: All specimens collected in this study represent color form untypical for this species, i.e., with the pronotum predominantly black and with yellow lateral patches ( Figure 2H). In typically colored P. nigripennis the pronotum is entirely yellow. Comparison of male and female genitalia of this form with those of typical form showed no differences. Distribution: Australian species, widely used as a biological control agent and established throughout the warmer regions of the world [31], including all seven islands of the Canary archipelago [3,18,19]. Distribution: European species [22]. In Macaronesia previously reported to be on the Azores [15]. New to the Canary Islands.

Nephus (Bipunctatus) bisignatus
Remarks: Both specimens of N. bisignatus that have been examined were chestnut brown in color which is probably teneral, while the typical coloration of mature beetles is black. Comparison of male genitalia of these specimens with those of typical form showed no differences. Distribution: Macaronesian species, reported to be on the Azores [15,32], Madeira [15,33,34], and all the Canary Islands [3].  Distribution: South European species [22], new to the Canary Islands. Distribution: Widely distributed in Europe and North Africa, and also reported to be from the Remarks: Kovář [22] treated S. durante (sic!) as a synonym of S. subvillosus. However, Eizaguirre [17] emphasized the distinctiveness of the Canarian populations of S. subvillosus, giving them the rank of subspecies. We comply with this decision. Distribution Widely distributed in the Mediterranean Basin and the Middle East, and also reported to be from the Afrotopical and Oriental regions [22]. Known from all Canary Islands except La Palma [3,18,19]. Distribution: Species reported to be on three islands of the Canarian archipelago, i.e., Fuerteventura, Tenerife, and Gran Canaria [3], and from Morocco [22].

Stethorus tenerifensis
Remarks: According to the body coloration (especially an elliptical dark spot in the central part of elytra) and other external characters of several specimens collected on Tenerife, Hodgson [38] described a new species, Lithophilus (=Tetrabrachys) tinerfensis. All those specimens were females and, hence, male genitalia could not be examined. In the Gran Canarian material presented in this study, we found specimens of both sexes with the elytral pattern either typical of T. tinerfensis ( Figure 4A) or T. deserticola ( Figure 4C), or intermediate between them (Figure 4B). Male genitalia in all of these color forms did not differ from those of T. deserticola shown by Romanowski et al. [18]. Therefore, we propose to synonymize Tetrabrachys tinerfensis (Hodgson, 1987) with Tetrabrachys deserticola (Wollaston, 1864).   Distribution: Western Palaearctic species [22] that probably relatively recently arrived in the Canary Islands. It was revealed for the first time by Eizaguirre [17] in the materials from the National Museum of Natural Sciences in Madrid collected on Tenerife, during the first half of 20th century. Later, it was recorded on Gran Canaria [39] and Fuerteventura [18]. Probably it was also recorded on La Palma and misidentified as Brumus quatuorpustulatus (sic!) (Linnaeus, 1758) by Hristova Gueorguieva [40]. This misidentified record is also quoted by Cocuzza et al. [41]. Distribution: This subspecies occurs mainly in North African countries. Reported to be on all the Canary Islands [3].
Remarks: Kovář [22] considers this taxon as a separate species, C. algerica, but according to Romanowski et al. [18] it should be treated as a subspecies of C. septempunctata. Distribution: Distributed in the Middle East, North Africa, and the Afrotropical region [22]. In May 1959, eight individuals of this species that arrived with stormy winds from Africa were collected in Santa Cruz de Tenerife [17]. The records presented here indicate that C. propinqua has established in the Canary Islands. New to Gran Canaria. Distribution: Endemic Canarian species, so far reported to be on La Palma and Tenerife [3]. New to Gran Canaria.

Coccinella miranda
Remarks: We examined only female specimens, however, the differences in the shape of coxites between N. conicollis and N. canariensis Korschefsky are distinct. In N. conicollis, coxites are more sclerotized with sides almost parallel. Very often the tip of ovipositor protrudes from the abdomen and can imitate the tip of the penis. In N. canariensis, coxites are sub-triangular and less sclerotized.  Distribution: Endemic Canarian species, so far reported to be on La Palma and Tenerife [3]. New to Gran Canaria.
Remarks: We examined only female specimens, however, the differences in the shape of coxites between N. conicollis and N. canariensis Korschefsky are distinct. In N. conicollis, coxites are more sclerotized with sides almost parallel. Very often the tip of ovipositor protrudes from the abdomen and can imitate the tip of the penis. In N. canariensis, coxites are sub-triangular and less sclerotized. Distribution: Macaronesian species, reported to be on Madeira [50] and all islands of the Canary archipelago [3,18,19].
Remarks: Previous reports of P. decemplagiatus from Gran Canaria [12,51,52] concern a color form described by Uyttenboogaart [12] as P. decemplagiatus ssp. grancanariensis. This form has been treated by many authors, for example, [3,16,17,52] as a separate species (P. grancanariensis). However, Kovář [22] considers P. grancanariensis a synonym of P. decemplagiatus. In the material collected in this study, we found a continuous variability between typically colored P. decemplagiatus and the form "grancanariensis". The genital organs within this series did not differ.
The immigration of species to the Canary Islands is probably more intense than that to many other oceanic archipelagos, due to the proximity of the former to the mainland. Northwestern Africa is certainly a very important source of species colonizing this archipelago [79]. On the one hand, the majority of species classified in this paper as presumed newcomers most likely arrived in the Canaries from that area., and their arrival could have happened in a natural way, for example, with the help of northeastern trade winds or Saharan sandstorms. On the other hand, ladybirds mentioned in Table 2 as alien species could not appear in the Canary Islands without human mediation. All of them have come from the remote continents and have been introduced in many parts of the world as biocontrol agents.
The detection on Gran Canaria of at least one more alien ladybird species is quite possible in the near future. Pharoscymnus flexibilis (Mulsant, 1853), a species of Asiatic origin, has recently been recorded on the two easternmost islands of the Canary archipelago, Fuerteventura [18] and Lanzarote [19]; on Fuerteventura, it was already widespread and common [18]. Assuming a high dispersal potential of P. flexibilis, its spread to further Canary Islands, first to the nearest Gran Canaria, can be expected.
Another candidate for an appearance on Gran Canaria is the well-known invasive ladybird, Harmonia axyridis. So far, however, there is no evidence of the establishment of this species within the Canary archipelago, and, since 2003, only single individuals have been recorded on Tenerife [17,80,81].
Unique biotas of oceanic islands, often showing high levels of endemism as compared with those in mainland regions are also highly susceptible to biotic perturbations, such as invasions by nonnative species [82,83]. The appearance of newcomers on the Canary Islands seems to be a frequent phenomenon, more frequent than on archipelagos more distant from continents and with less intense tourism. A good illustration of this is the ladybird fauna on Gran Canaria and other islands of the archipelago, which is regularly disturbed by immigrants of various origins.
Funding: This research was partially funded by the En Arche foundation, grant number 2020/01/15 to J.R.