Streptaxidae


Streptaxidae is a family of carnivorous air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade
Stylommatophora.
Streptaxidae are monophyletic while all subfamilies and several genera are polyphyletic.
Six Streptaxidae subfamilies are accepted in the 2005 taxonomy of the Gastropoda by Bouchet & Rocroi.
Streptaxidae are carnivorous except for one species Edentulina moreleti, which is herbivorous. All streptaxids have well-developed radula, except Careoradula perelegans, which is the only known terrestrial gastropod without radula.
Altogether 66 species from the family Streptaxidae are listed in the 2010 IUCN Red List.

Distribution

The historical area of origin of the Streptaxidae is probably Gondwanaland.
The family is widely distributed across the tropical and subtropical areas of South America, Africa and Asia. The Recent native distribution of Streptaxidae includes South America, Africa, Arabia, Madagascar, Seychelles, Mayotte, Comores, Mauritius, Réunion, Rodrigues, India, Sri Lanka, Andamans, South-East Asia and the Philippines. The genus Gibbulinella is found in the Canary Islands.
The species diversity of Streptaxidae reaches its maximum in sub-Saharan Africa.
With 13 genera and about 130 nominal species, the second most diverse streptaxid fauna can be found in Southeast Asia. Streptaxidae are the most diverse among tropical Asian carnivorous snails. In Indochina, streptaxid diversity was thought to comprise only 10 genera and about 40 species in 1967. However, in 2006–2016, 21 new species and one new genus had been described from Indochina. Thirty-seven species are recorded from Thailand, 10 from Myanmar, 45 from Vietnam, and 12 from Laos.

Description

Streptaxids can generally be recognized by their eccentric or cylindrical shells, while the animals have a bright yellow to red or orange body with external hook-like structures on the everted penis.
Early classifications of the family such as Wilhelm Kobelt, used mainly shell shape and the arrangement of apertural dentition. However, many shell characters are highly conserved or occur recurrently, making some species and genera difficult to separate. The reproductive organs of streptaxids can also be taxonomically significant.

Taxonomy

Prior to Schileyko's revision in 2000 only two subfamilies, the Streptaxinae and the Enneinae had been recognized, which were primarily based on their shell morphology.

2005 taxonomy

Only the one family, Streptaxidae, was recognized within the Streptaxoidea in the taxonomy of Bouchet & Rocroi (2005).
There are 7 subfamilies in the family Streptaxidae according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, that follows Schileyko :
  • Enneinae Bourguignat, 1883 - synonym: Streptostelidae Bourguignat, 1889
  • Gulellinae Rowson, 2024
  • Marconiinae Schileyko, 2000
  • Odontartemoninae Schileyko, 2000
  • Orthogibbinae Germain, 1921 - synonyms: Gibbinae Steenberg, 1936; Gonidominae Steenberg, 1936
  • Primigulellinae Rowson, 2024
  • Streptaxinae Gray, 1860 - synonym: Artemonidae Bourguignat, 1889
;Synonyms:
  • Ptychotrematinae Pilsbry, 1919: synonym of Enneinae Bourguignat, 1883

    2010 taxonomy

Sutcharit et al. have established a new family Diapheridae within Streptaxoidea and they have added two genera Diaphera and Sinoennea into Diapheridae.
The later review "A review of the Diapheridae" in 2020 by Páll-Gergely, B., Hunyadi, A., Grego, J., Sajan, S., Tripathy, B. & Chen, Z.-Y. showed the family Diapheridae to stand separate from Streptaxidae.
In the recent decades, most of the taxonomic and systematic research on streptaxids has been performed on sub-Saharan African taxa. Only a few publications focus on South American or Asian groups.

Genera

Genera in the family Streptaxidae include:

Enneinae

;Notes:
  • Scolodonta Doering, 1875 used to be classified within Streptaxinae, but Scolodonta is the type genus of the family Scolodontidae.

    Synonyms

  • Subfamily Gibbinae Steenberg, 1936: synonym of Orthogibbinae Germain, 1921
  • Subfamily Gonidominae Steenberg, 1936: synonym of Orthogibbinae Germain, 1921
  • Subfamily Ptychotrematinae Pilsbry, 1919: synonym of Enneinae Bourguignat, 1883
  • Aberdaria Blume, 1965: synonym of Primigulella Pilsbry, 1919
  • Acanthenna: synonym of Acanthennea E. von Martens, 1898
  • Adjua Chaper, 1885: synonym of Ptychotrema Chaper, 1885 represented as Ptychotrema L. Pfeiffer, 1853
  • Alcidia Bourguignat, 1890: synonym of Streptaxis Gray, 1837
  • Artemon H. Beck, 1837: synonym of Streptaxis Gray, 1837
  • Campylaxis Ancey, 1888: synonym of Streptostele Dohrn, 1866
  • Carychiopsis E. von Martens, 1895: synonym of Ennea H. Adams & A. Adams, 1855: synonym of Ptychotrema H. Adams & A. Adams, 1855 represented as Ptychotrema L. Pfeiffer, 1853
  • Colpanostoma Bourguignat, 1890: synonym of Tayloria Bourguignat, 1890 represented as Tayloria Bourguignat, 1890
  • Conogulella Pilsbry, 1919: synonym of Gulella Pilsbry, 1919 represented as Gulella L. Pfeiffer, 1856
  • Ennea H. Adams & A. Adams, 1855 - type genus of the subfamily : synonym of Ptychotrema H. Adams & A. Adams, 1855 represented as Ptychotrema L. Pfeiffer, 1853
  • Enneastrum L. Pfeiffer, 1856: synonym of Ennea H. Adams & A. Adams, 1855: synonym of Ptychotrema H. Adams & A. Adams, 1855 represented as Ptychotrema L. Pfeiffer, 1853
  • Eustreptaxis L. Pfeiffer, 1878: synonym of Streptaxis Gray, 1837
  • Eustreptostele Germain, 1915: synonym of Streptostele Ancey, 1885: synonym of Tomostele Ancey, 1885
  • Gibbonsia Bourguignat, 1890: synonym of Gigantaxis Tomlin, 1930: synonym of Tayloria Bourguignat, 1890 represented as Tayloria Bourguignat, 1890
  • Gibbulina Beck, 1837: synonym of Gibbus Montfort, 1810
  • Gigantaxis Tomlin, 1930: synonym of Tayloria Bourguignat, 1890 represented as Tayloria Bourguignat, 1890
  • Haplonepion Pilsbry, 1919: synonym of Ptychotrema Pilsbry, 1919 represented as Ptychotrema L. Pfeiffer, 1853
  • Huttonella Pfeiffer, 1855: synonym of Gulella L. Pfeiffer, 1856 represented as Gulella L. Pfeiffer, 1856
  • Idolum L. Pfeiffer, 1856: synonym of Gonidomus Swainson, 1840
  • Indoennea Kobelt, 1904: synonym of Sinoennea Kobelt, 1904
  • Ischnostele C. R. Boettger, 1915: synonym of Streptostele Bourguignat, 1883 represented as Streptostele Dohrn, 1866
  • Luntia E.A. Smith, 1898: synonym of Streptostele Ancey, 1885: synonym of Tomostele Ancey, 1885
  • Marconia Bourguignat, 1889 - type genus of the subfamily: synonym of Gonaxis J. W. Taylor, 1877
  • Macrogonaxis Bequaert & Clench, 1936: synonym of Tayloria Thiele, 1932 represented as Tayloria Bourguignat, 1890
  • Marconia Bourguignat, 1890: synonym of Gonaxis J. W. Taylor, 1877
  • Maurennea: synonym of Gulella Schileyko, 2000 represented as Gulella L. Pfeiffer, 1856
  • Nevillia E. von Martens, 1880: synonym of Microstrophia Möllendorff, 1887
  • † Oppenheimiella Pfeffer, 1930 : synonym of † Pfefferiola Harzhauser & Neubauer, 2021
  • Orthogibbus Germain, 1919: synonym of Gonospira Swainson, 1840
  • Parennea Pilsbry, 1919: synonym of Ptychotrema Pilsbry, 1919 represented as Ptychotrema L. Pfeiffer, 1853
  • Pseudartemon J. Mabille, 1887: synonym of Haploptychius Kobelt, 1905
  • Raffraya Bourguignat, 1883: synonym of Streptostele Bourguignat, 1883 represented as Streptostele Dohrn, 1866
  • Sinistrexcisa de Winter, Gómez & Prieto, 1999: synonym of Ptychotrema L. Pfeiffer, 1853
  • Somalitayloria Verdcourt, 1962: synonym of Tayloria Verdcourt, 1962 represented as Tayloria Bourguignat, 1890
  • Stenomarconia Germain, 1934: synonym of Gonaxis Germain, 1934 represented as Gonaxis J. W. Taylor, 1877
  • Thaumatogulella F. Haas, 1951: synonym of Mirellia Thiele, 1933
  • Varicostele Pilsbry, 1919: synonym of Streptostele Pilsbry, 1919 represented as Streptostele Dohrn, 1866
  • Webbia Odhner, 1932: synonym of Gibbulinella Wenz, 1920