Resurrection of Synema globosum canariense Dahl, 1907 (Araneae: Thomisidae) with comments on other synonyms within this genus

Abstract

Synema globosum (Fabricius, 1775) is a crab spider that ambushes insects on leaves and on flowers of herbs and shrubs. Being a predator of florivores and other herbivores it may lower herbivore damage on some plant species, as shown for Erophaca baetica (L.), Boiss. (Canterbury 2019). Crab spiders using flowers as capture sites may also alter the structure of communities of flower-visiting insects, and thereby influence plant pollination (Marrero et al. 2015). Taxonomy is crucial for studying such ecological interactions because it clearly identifies the species involved. As in the case of many other genera, our view of Synema has evolved over time with species being added, synonymized, or transferred. Several subspecies have been erected, but nearly all were later synonymized with the nominotypical subspecies (WSC 2023). The genus currently holds 124 accepted species including S. globosum, which also is the type species (WSC 2023).According to the current understanding Synema globosum is widely distributed in the Palaearctic realm, ranging from the Canary Islands to Eastern Asia (Nentwig et al. 2023, Ono 1988, WSC 2023, Wunderlich 1987. In Europe it is found in Southern Europe, Western Europe, and the southern half of Eastern Europe (Nentwig et al. 2023). It is particularly common in the Mediterranean region, which also includes Tunisia, Algeria, and Morocco (Nentwig et al. 2023). It is not known whether the species has become established in Northern Europe. In recent years it has been recorded several times in England, but there is as yet no evidence of established populations (Bee et al. 2020).A well-known feature of S. globosum is the variation in colour among specimens, being much more pronounced in females than in males (Fig. 1). The opisthosoma (folium ex-cepted) can be coloured in shades of either white, yellow, orange, or red. Some specimens are bicoloured, but with one colour dominating (Fig. 1: F4, F5, M1). The dorsum of the opisthosoma has a broad, foliaceous, black pattern (rarely brown), and the anterior part resembles the outline of a bicorne hat. Hence, the vernacular name of this species is 'Napoleon Spider'. The head is brown to dark brown, and the front 1 st and 2 nd pairs of legs are dark brown to blackish with paler annulations distally. The 3 rd and 4 th pairs of legs are both shorter and paler than the front legs. The species exhibits sexual dimorphism, males are smaller and darker and with less colour variation compared to females.According to the Canary Islands Government (2022), S. globosum is the only Synema species listed from the islands, with records from Gran Canaria, Tenerife, La Gomera and La Palma. In 2011, Synema specimens were beaten from bushes in the pine forest belt on the southern slopes of Tenerife. Due to their general appearance it seemed unlikely that these specimens belonged to S. globosum, as their colour markings differed significantly from those of specimens from the European mainland. Later, more specimens from the islands of La Gomera and Gran Canaria were collect...