Endosomatium, Wollaston, 1877

Maddison, David R, Sproul, John S & Mendel, Howard, 2020, Origin and adaptive radiation of the exceptional and threatened bembidiine beetle fauna of St Helena (Coleoptera: Carabidae), Zoological Journal of the Linnean Society 189 (4), pp. 1155-1175 : 1165-1166

publication ID

https://doi.org/10.1093/zoolinnean/zlz150

persistent identifier

https://treatment.plazi.org/id/0392C86B-6A4C-BF66-04E0-C2D0FA6AA05D

treatment provided by

Plazi

scientific name

Endosomatium
status

 

Endosomatium and Pseudophilochthus were unrelated,

each representing a separate dispersal event onto St Helena by different lineages of bembidiines. However, Pseudophilochthus + Apteromimus + Endosomatium form a clade ( Figs 7 View Figure 7 , 8 View Figure 8 ; Table 3). A unique common ancestor of the Peaks Bembidion is supported by individual analyses of five of the seven genes examined and is strongly supported by the concatenated analyses ( Table 3). Thus, it appears that the extraordinary diversity of body forms of St Helena Peaks Bembidion arose from a single ancestor that arrived within the last 14 Myr and diversified into the 12 endemic species known today.

In spite of their morphological disparities, the genetic divergence of the four species whose DNA was sequenced is not at all remarkable, showing no more diversity ( Figs 7 View Figure 7 , 9 View Figure 9 ) than within the morphologically fairly uniform subgenus, Omotaphus ( Fig. 5A–C View Figure 5 ). This pattern of extreme phenotypic divergence but limited genetic divergence matches that in some other island radiations. For example, the plant genus Bidens ( Asteraceae ) shows more morphological diversity among the 19 species in Hawai’i than it does throughout the entirety of the Americas, and yet the total genetic diversity in Hawai’i is comparable to that found within individual species of mainland Bidens ( Helenurm & Ganders, 1985) .

The St Helena Peaks Bembidion appears to have undergone a classical adaptive radiation ( Schluter, 2000; Gavrilets & Losos, 2009). The ecological opportunity provided by arrival on a depauperate island with few small predators, and perhaps none

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Carabidae

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