Genus Cyathostomum Molin, 1861 Hartwich, 1986

Synonyms: Trichonema Cobbold, 1874; Cylicostomum Looss in Railliet, 1901; Cylichnostomum Looss, 1902; Cylicostoma Looss, 1911; Cylicocerus Ihle, 1922; Cylicostomias Cram, 1925.

General. Medium-sized Cyathostominea. MC inflated, high, ring-shaped, divided into inner and outer rings. Posterior edge of MC situated at, anterior, or posterior to anterior edge of BC. Amphids not markedly projected through MC surface. Tip and longer stalk of submedian papillae extend through MC. Tip of submedian papillae bullet-shaped, 2 – 3 times as long as thick. Stalk of submedian papillae longer than broad. ELC markedly less numerous and longer than ILC. Elements of ELC longer than broad, tip pointed; insertion point slightly back from tips of elements of ILC. Elements of ILC longer than broad, tips pointed; insertion point about ¼ to ½ of BC depth. Line formed by insertion of elements of ILC curved or sinuous. Form of posterior edge of elements of ILC straight, unadorned. Support for ELC continuous with BC, elongate, curving, thin at one end. Septum intracoronare origin on support. Medial insertion of septum intracoronare situated anteriorly to junction of ELC and ILC. Walls of BC straight, thicker posteriorly, but without ring-like thickening. Buccal cavity cylindrical, wider than deep. Dorsal gutter nipple- or button-like. Buccal teeth absent. Esophageal funnel shallow. Esophageal teeth not prominent. Anterior muscular portion of esophagus about ¼ to 1/3 of esophagus length. Excretory pore posterior to NR. Anterior deirids near middle of glandular esophagus.

Male: Dorsal ray with 6 branches. Ventral rays shorter or of equal length to laterals (longer in C. alveatus). Dorsal lobe longer then lateral lobes. Externodorsal rays origin at junction of dorsal and laterals rays. Gubernaculum large, with dorsal handle and ventral notch. Genital cone short, conical. Spicule tips pick-shaped.

Female: Vulva about one, or less than one, tail length from anus. Vagina longer than sphincter. Ovejector vestibule oval or Y-shaped, infundibulum longer than sphincter. Tail digitiform, short, length less than 2x diameter at anus.

Type species: C. tetracanthum (Mehlis, 1831) Molin, 1861, in part; Looss, 1900

Discussion

The validity of the genus Cyathostomum and its type species C. tetracanthum have had a contentious history (Lichtenfels, 1975; Gibbons and Lichtenfels, 1999). The validity of Cyathostomum and its type species were finally established recently by the International Commission on Zoological Nomenclature (ICZN) (Opinion 1972 on Case 3075, June 2001). A few highlights of the history of the controversy and its solution are summarized here. Molin (1861) established Cyathostomum with Strongylus tetracanthus as the type species by monotypy. Looss (1900) recognized that Molin’s C. tetracanthum included several species and restricted the name to the most common species found by him in Egypt. Railliet (1923) proposed that Cyathostomum was a homonym of Cyathostoma Blanchard, 1849 and established Trichonema Cobbold, 1874. For many years both Trichonema and Cyathostomum were used for overlapping groups of species. Mclntosh (1951) established that Cyathostomum was not a homonym and listed a synonymy of the type species. Lichtenfels (1975) reviewed the history of the controversary and followed McIntosh’s recognition of Cyathostomum, with C. tetracanthum as the type species. Hartwich (1986) discovered Mehlis (1831) type series of C. tetracanthum and determined that the species designated by Looss (1900) as C. tetracanthum is not present among Mehlis' specimens. Hartwich selected and renamed C. catinatum Looss, 1900 as the true C. tetracanthum and renamed Looss' C. tetracanthum as C. aegyptiacum. In the interest of stability, the Sun City Workshop (Lichtenfels et al., , 1998) voted (with the concurrence of Dr. Gerhard Hartwich) to ask the International Commission on Zoological Nomenclature to validate the names of these species in use prior to Hartwich's proposal Gibbons and Lichtenfels, 1999). Only Dvojnos and Kharchenko (1994) had followed Hartwich and referred to C. catinatum as C. tetracanthum. The ICZN ruled (Opinion 1972, 2001) “Ruling

(1) Under the plenary power all previous fixations of' type specimens for the nominal species Strongy1us tefractinthus Mehlis, 1831 are hereby set aside and the specimen no. 087757.00 in the U.S. National Parasite Collection, Beltsville, Maryland, collected by A. Looss in 1899, is designated as the neotype.

(2) The name Cvathostonmm Molin, 1861 (gender: neuter), type species by monotypy Strongy1us tetracanthus Mehlis, 1831, is hereby placed on the Official List of Generic Names in Zoology.

(3) The following names are hereby placed on the Official List of Specific Names in Zoology:

(a) tetracanthus Mehlis, 1831, as published in the binomen Strong.vlus tetracanthus and as defined by the neotype designated in (1) above (specific name of the type species of Cyathostoinum Molin, 1861),

(b) catinaum Looss, 1900, as published in the binornen Cyathostomum cainatuml.

(4) The following names are hereby placed on the Official Index of Rejected and Invalid Generic Names in Zoology:

(a) Cvlichnostomum Looss, 1901 (a junior objective synonym of? Cyafhostomum I Molin, 1861),

(b) Cylicostomian Railliet, 1901 (a junior objective synonym of'('Yathostomlan Molin, 1861).

(5) The following names are hereby placed on the Official Index of Rejected and Invalid Specific Names in Zoology:

(a) hexacanthum Wedl, 1856, as published in the binomen Sclerostoma hex(tcanthum (a junior objective synonym of' Strongy1its telracanthus Mehlis, 1831)

(b) aegyptiactim Raillict, 1923, as published in the hinornen Tri(honcma aegyptiacum and as defined by the lectotype designated by Gibbons & Lichtenfels (1999) (a junior objective svnonym of Strongvlus teiracmithus Mehlis, 1831).”

Lichtenfels (1975) expanded McIntosh’s (1951) concept of Cyathostomum to include 9 species. Hartwich (1986) moved 4 of the 9 species to a new genus, Coronocyclus. We (Lichtenfels et al., 1998) agreed with Hartwich,s establishment of Coronocyclus and now include only 5 species in Cyathostomum.