GELASTOCORIDAE Kirkaldy, 1897

Polhemus, Dan A. & Polhemus, John T., 2012, Guide To The Aquatic Heteroptera Of Singapore And Peninsular Malaysia. Ix. Infraorder Nepomorpha, Families Ochteridae And Gelastocoridae, Raffles Bulletin of Zoology 60 (2), pp. 343-359 : 356

Family GELASTOCORIDAE Kirkaldy

Discussion. — Gelastocoridae , or “ toad bugs ”, are easily recognised among the nepomorphan families by their rough and sculptured body surface, large eyes, presence of ocelli, the broad and flap-like labrum, four-segmented antennae lacking finger-like projections, enlarged raptorial fore femora, the tarsal formula of 1-2-3, unequal development of the claws on the forelegs, and asymmetrical genitalia with the right paramere large and often elaborated, and the left reduced or absent. As noted earlier, a number of these character states, as well as a riparian ecology, are shared with the Ochteridae . Among the local assemblage of Southeast Asian species, characters of particular use in individual species discrimination include the arrangement of tubercles on the head, the shape of the pronotum, and the shape of the male right paramere ( Figs. 36, 38 ). In contrast to Ochteridae , dorsal coloration is not a particularly useful species-specific character, and is in any case often obscured by mud and dirt, which covers many mature specimens and further serves to camouflage living individuals in the field.

The Gelastocoridae are also similar to the previously treated Ochteridae in being a pantropical family with two distinct foci of species radiation in the Neotropical and Melanesian regions, and limited species richness elsewhere. Three genera are currently recognised: the Neotropical Gelastocoris and Montandonius , and the widespread Nerthra (see Todd, 1955). Only the latter genus occurs in Singapore and Malaysia. The gelastocorid species occurring on continental Southeast Asia and the proximal Greater Sunda Islands were recently treated by Kment & Jindra (2008), and the reader is referred to that work for a more comprehensive treatement of the Asian fauna. The family is probably more diverse and widespread in tropical Asia than is currently understood, with many of the species occurring in this region being known from very limited material. Pitfall trapping is a particularly effective method for collecting gelastocorids, and more concerted effort in this regard, particularly in areas of relatively undisturbed rainforest, has the potential to yield valuable insights related to the distribution and ecological associations of these unusual insects.

Figures

Figs. 36–38. Nerthra species, structural details (after Todd, 1955). 36, N. lobata, male right paramere. 37, N. lobata, female terminal abdomen, ventral view showing paired processes. 38, N. macrothorax, male right paramere, apical section.