Premium
The occipital region in the basal Hymenoptera (Insecta): a reappraisal
Author(s) -
Vilhelmsen Lars
Publication year - 1999
Publication title -
zoologica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 64
eISSN - 1463-6409
pISSN - 0300-3256
DOI - 10.1046/j.1463-6409.1999.00008.x
Subject(s) - bridge (graph theory) , synapomorphy , hymenoptera , biology , anatomy , basal (medicine) , evolutionary biology , zoology , paleontology , phylogenetics , genetics , insulin , endocrinology , clade , gene
The occipital region in representatives of all the ‘symphytan’ families and a few apocritans is investigated. A new character, the occurrence of occipital sulci, is described. The absence of occipital sulci and corresponding internal ridges is a putative synapomorphy for the Xiphydriidae, Orussoidea, and Apocrita. Independent loss has occurred in the cimbicid genus Zaraea . The evolution of sclerotizations between the occipital and oral foramina in basal Hymenoptera is discussed. A postoccipital bridge, an internal structure formed by the fusion of the apodemes for the profurco‐postoccipital muscles, forming a ventral connection between the tentorial arms, is present in Cimbex , Cephoidea, and Syntexis . An external sclerotization, the hypostomal bridge, is present in Corynis , Cephoidea, ‘Siricoidea’, Orussoidea, and Apocrita. In Syntexis , the postoccipital and hypostomal bridges are continuous. It is difficult to decide whether a hypostomal bridge is also present in the Pamphilioidea, or the external sclerotization in this superfamily has evolved independently. In the Siricidae, Orussidae, and some Apocrita, a postgenal bridge largely replaces the hypostomal bridge. The postgenal bridge has evolved at least twice independently in the Hymenoptera.