From four- to three-segmented labium in Reduviidae (Hemiptera: Heteroptera)

Weirauch Christiane
Acta Entomologica Musei Nationalis Pragae 48(2): 331-344, 2008
Views: 90
Abstract: The majority of Reduviidae – unlike most other Heteroptera – has a labium that consists of only three segments. The first segment is said to be either lost or fused to the head capsule. Cladistic analysis shows that this loss or fusion occurred once or twice among basal Reduviidae and that the four-segmented labium in Hammacerinae is plesiomorphic and homologous to the one in non- reduviid Cimicomorpha. In the present contribution, extrinsic labial muscles and sclerites associated with the base of the labium are documented (micro-dissecti- ons, histology) for Himacerus apterus (Fabricius, 1789) (Nabidae), Microtomus purcis (Drury, 1782) (Reduviidae: Hammacerinae) and Rhynocoris erythropus (Linnaeus, 1767) (Reduviidae: Harpactorinae). Primary homology hypotheses are proposed on lever, depressor, and transverse muscles among the examined taxa and previously published descriptions of Nepomorpha and Leptopodomorpha. The two Reduviidae are unique in having a large portion of the Musculus levator labii (muscle A) originating from the first labial segment (M. purcis) or the gena (R. erythropus). This may indicate that part of the gena is homologous to part of the first labial segment, i.e. the proximal portion of the first labial segment may be fused to the gena, but migration of the muscle origin may also account for this condition. The insertion of M. transversalis labii has shifted from the dorsal surface of the first labial segment to the anterior portion of the suspensory plate, possibly indicating that this structure may include part of the first labial segment. Even though the first labial segment is not visible externally in the majority of Reduviidae, two muscles that were originally associated with it are thus retained. Mapped on a phylogeny of Reduvioidea it seems evident that in a first step the levator muscle became larger at the base of the Reduviidae. In a second step the first labial segment fused to the head capsule, possibly providing this enlarged muscle with a more solid origin.
Key words: Reduviidae, morphology, labium, histology, muscle, phylogeny
Papers
We are celebrating the seventy-fifth anniversary of Professor Pavel Štys’ birthFour chapters about the monophyly of insect ‘orders’: A review of recent phylogenetic contributionsA new species of Systelloderes (Hemiptera: Heteroptera: Enicocephalidae) from South AfricaTwo new species of Kokeshia from India and Thailand (Hemiptera: Heteroptera: Schizopteridae)Evolution of the semi-aquatic bugs (Hemiptera: Heteroptera: Gerromorpha) with a re-interpretation of the fossil recordNotes on aquatic and semiaquatic bugs (Hemiptera: Heteroptera: Nepomorpha, Gerromorpha) from Malesia with description of three new speciesA new Indian Ocean species of Ochterus from the island of Mauritius (Hemiptera: Heteroptera: Ochteridae)Intraspecific morphological polymorphism in Naucoridae (Hemiptera: Heteroptera) with notes on nomenclature and synonymyStructure and development of the reproductive system in Aphelocheirus aestivalis (Hemiptera: Heteroptera: Nepomorpha: Aphelocheiridae)Notes on the endemic Philippine genus Orthosaldula (Hemiptera: Heteroptera: Saldidae), with descriptions of two new speciesFrom four- to three-segmented labium in Reduviidae (Hemiptera: Heteroptera)Two new species of the emesine assassin bug genus Ploiaria (Hemiptera: Heteroptera: Reduviidae) from IndonesiaOncocephalus stysi, a new species of Stenopodainae (Hemiptera: Heteroptera: Reduviidae) from IsraelNew records of Scotomedes alienus sikkimensis (Hemiptera: Heteroptera: Velocipedidae) from NepalFulvius stysi, a new species of Cylapinae (Hemiptera: Heteroptera: Miridae) from Papua New GuineaStysiofulvius, a new genus of Cylapinae (Hemiptera: Heteroptera: Miridae) from the Peninsular MalaysiaA new species of the genus Phytocoris (Hemiptera: Heteroptera: Miridae)Acetropis stysi, a new species from Spain (Hemiptera: Heteroptera: Miridae)A review of the Far East Asian mirine plant bug genus Loristes (Hemiptera: Heteroptera: Miridae: Mirinae), with description of a new species from JapanThree new species of Phylini (Hemiptera: Heteroptera: Miridae: Phylinae) from Central AsiaA new species of Megalocoleus (Hemiptera: Heteroptera: Miridae: Phylinae) from MoroccoTwo new Phylinae (Hemiptera: Heteroptera: Miridae) from the Canary IslandsSystematics, biogeography and host associations of the lace bug genus Inoma (Hemiptera: Heteroptera: Tingidae)Phymacysta stysi, a new species of lace bug from Dominican amber (Hemiptera: Heteroptera: Tingidae: Tinginae)New data on the Tingidae from Gabon (Hemiptera: Heteroptera)Pavlostysia wunderlichi gen. nov. and sp. nov., the first fossil spider-web bug (Hemiptera: Heteroptera: Cimicomorpha: Plokiophilidae) from the Baltic Eocene amberRajburicoris, a new genus of Cardiastethini, and discussion of the systematic position of Dufouriellus (Hemiptera: Heteroptera: Anthocoridae)A pair of basi-abdominal sex pheromone glands in the male of some burrower bugs (Hemiptera: Heteroptera: Cydnidae)New subtribes and a new genus of Podopini (Heteroptera: Pentatomidae: Podopinae)Two new species of the genus Chloropepla (Hemiptera: Pentatomidae: Pentatominae) from BrazilA revision of the endemic Madagascan genus Triplatyx (Hemiptera: Heteroptera: Pentatomidae)Massocephalus stysi, a new species of Pentatomidae (Hemiptera: Heteroptera) from the PhilippinesA revision of the Entisberus group (Hemiptera: Heteroptera: Rhyparochromidae)New taxa of the Largidae and Pyrrhocoridae (Hemiptera: Heteroptera) from the Oriental RegionTwo new species of Anasa (Hemiptera: Heteroptera: Coreidae: Coreini) from Mexico and Central AmericaA review of the genus Satonius (Coleoptera: Myxophaga: Torridincolidae): taxonomic revision, larval morphology, notes on wing polymorphism, and phylogenetic implicationsTaxonomic changes within the tribe Hyperini (Coleoptera: Curculionidae)Tachysphex stysi sp. nov. (Hymenoptera: Apoidea: Crabronidae) from Central Asia