Pneumoridae

The Pneumoridae are a family of nocturnal short-horned grasshoppers in the order Orthoptera, commonly known as the bladder grasshoppers and the sole representative of the superfamily Pneumoroidea.[1] Their centre of diversity is in southern Africa, but one species occurs as far north as South Sudan. Most adult males acquire an inflated abdomen, a specialization for amplified sound production, which is likely its primary function. Most genera display striking sexual dimorphism,[2] and several species exhibit a dual male phenotype.[3]

Pneumoridae
Bullacris intermedia
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Orthoptera
Suborder: Caelifera
Infraorder: Acrididea
Informal group: Acridomorpha
Superfamily: Pneumoroidea
Blanchard, 1845
Family: Pneumoridae
Blanchard, 1845
Genera

see text

Description

They are nocturnal, specialized herbivores which (with few exceptions) are endemic to coastal regions of southern Africa.[1] The smallest species is Pneumoracris browni occurring in the Succulent Karoo ecoregion, while the largest is the wide-ranging Afromontane forest species, Physophorina livingstoni.

lateral ocelli relative
to antennal bases		genus[2]
above and slightly internallyBullacris and related genera
intermediate positionProstallia
above and slightly externallyPhysophorina and Pneumora

Sexual dimorphism

The body length of adult males vary from 11.5 to 68.0 mm, and that of females from 22.0 to 107 mm. Males of a particular species may or may not have an inflated body with fully developed wings, or both morphs may be present. Males have large ocelli, a prominently crested pronotum, and are smaller in size. Females' bodies are larger and not inflated, and possess only reduced elytra and wings. Female ocelli are vestigial and the pronotum is more tectiform, while the sound-producing mechanism is entirely different.[2]

Males

Adult males of most species acquire an inflated, bladder-like abdomen at the final molt. Their abdominal segments consist of a thin, semitransparent integument, and are enlarged in length and width, while the intersegmental membranes are much reduced.[2] Males are capable of producing loud calls, a long and very deep rasping noise,[2] which members of their species can detect from 2 km away. Males call by stridulating the rasp on the inner surface of their rather weak hind femur against an opposing rasp on the third tergite of the inflated, hollow abdomen. These sclerotized abdominal ridges form a crescent-like row, and their exact number has some value in distinguishing between taxa.[2] In species without an inflated body, these characters are only vestigial. The wings of males have a primitive morphology, and are not suited to producing sound.[4] Their wing venation is in fact the simplest of all the Acridoidea.[2]

Females

Females reply by duetting.[1] They employ a different sound mechanism to produce a distinguishable call, sometimes described as a high squeak, and perhaps only partially audible to humans. This is perhaps produced by rubbing strong wing veinlets armed with strong teeth against the abdomen, which is facilitated or accompanied by raising the pronotum at a high angle.[2]

Ecology

Within one species, a primary (plesiomorph) and alternative (apomorph) male form with differing mating strategies can arise. Details of these morphs were the basis for the description of two subfamilies, namely Pneumorinae (Dirsh 1975) and Parabullacrinae (Dirsh 1975). Three groups are distinguishable on the basis of their ecology, namely a forest, marginal, and desert group, of which the forest species are the most primitive.[5]

Genera and species

List of genera and species:[1][6]

Genus Bullacris Roberts, 1941

  • B. boschimana (Péringuey)
Range: Northern Cape
  • B. discolor (Thunberg)
Range: Western Cape and Eastern Cape, Habitat: Fynbos
Phenotype: Inflated and uninflated males
  • B. intermedia (Péringuey)
Range: Eastern Cape and KwaZulu-Natal
  • B. membracoides (Walker)
Range: Eastern Cape, KwaZulu-Natal and Malawi, Habitat: Savanna
Phenotype: Inflated and uninflated males
  • B. obliqua (Thunberg)
Range: Western Cape, Habitat: Fynbos
Phenotype: Inflated and uninflated males
  • B. serrata (Thunberg)
Range: Western Cape and Eastern Cape
  • B. unicolor (Linnaeus)
Range: Cape provinces, Habitat: Succulent Karoo
Phenotype: Only inflated males

Genus Parabullacris Dirsh, 1963

  • P. vansoni Disrch
Range: Northern Cape, Habitat: Succulent Karoo
Phenotype: Only uninflated males

Genus Physemacris Roberts, 1941

  • P. papilosus (Fabricius)
Range: Western Cape
  • P. variolosus (Linnaeus)
Range: Western Cape, Habitat: Fynbos
Phenotype: Only inflated males

Genus Paraphysemacris Dirsh, 1963

  • P. spinosus Dirsh
Range: Cape provinces, Habitat: Fynbos
Phenotype: Only uninflated males

Genus Peringueyiacris Dirsh, 1965

  • P. namaqua (Péringuey)
Range: Northern Cape, Habitat: Succulent Karoo
Phenotype: Only inflated males

Genus Pneumoracris Dirsh, 1963

  • P. browni Dirsh
Range: Northern Cape, Habitat: Succulent Karoo
Phenotype: Only uninflated males

Genus Prostallia Bolivar, 1906

  • P. granulata (Stål)
Range: KwaZulu-Natal and Mpumalanga

Genus Physophorina Westwood, 1874

  • P. livingstoni Westwood
Range: South Africa, Mozambique, Malawi, Tanzania, Uganda and South Sudan, Habitat: Forest
Phenotype: Only inflated males
  • P. miranda (Péringuey)
Range: South Africa and Tanzania, Habitat: Forest
Phenotype: Only inflated males

Genus Pneumora Thunberg, 1775

  • P. inanis (Fabricius)
Range: South Africa and Tanzania, Habitat: Forest
Phenotype: Only inflated males

References
  1. Donelson, Nathan C.; van Staaden, Moira J. (10 May 2005). "Alternate tactics in male bladder grasshoppers Bullacris membracioides (Orthoptera: Pneumoridae)". Behaviour. 142: 761–778. CiteSeerX 10.1.1.552.8161. doi:10.1163/1568539054729088.
  2. Dirsh, V. M. (1965). "Revision of the Family Pneumoridae (Orthoptera: Acridoidea)". Bulletin of the British Museum (Natural History) Entomology. 15 (10): 323–396. Retrieved 10 January 2017.
  3. Donelson, Nathan (December 2007). "Inter- and Intraspecific variation in the Superfamily Pneumoroidea". DPhil dissertation. OhioLink. Retrieved 11 January 2017.
  4. Smart, John (20 August 2009). "On the wing-venation of Physemacris variolosa (Linn.) (Insecta: Pneumoridae)". Proceedings of the Zoological Society of London. 123 (1): 199–202. doi:10.1111/j.1096-3642.1953.tb00165.x.
  5. Bruton, Michael N.; Alexander, Anne J.; van Staaden, Moira (1989). Alternative Life-History Styles of Animals. Dordrecht: Springer Netherlands. pp. 261–276. ISBN 9789400926059.
  6. van Staaden, Moira. "Family: Pneumoridae". A Catalogue of South African Insects. Rhodes University. Retrieved 9 January 2017.
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