Subdivision

Historically, up to 1973, Trichodorus was the only genus in this family. Originally it was the only genus in a subfamily, the Trichodorinae Thorne 1935,^[1] within the family Diphtherophoridae, to distinguish it from the other subfamily, Diphtherophorinae.^[8] However Diphtherophoridae was elevated to superfamily rank, and the subfamily Trichodorinae became a full-fledged family.^[9] The genus Trichodorus was split into two genera in 1974 by Siddiqi,^[10] Trichodorus and Paratrichodorus. This was based on the position of the gland nuclei and the type of pharyngo-intestinal junction. Siddiqi also used these criteria to divide Paratrichodirus into three subgenera, Paratrichodorus, Atlantadorus and Nanidorus. Rodriguez-Montessorosoon proposed further separating these genera into two subfamilies, resurrecting the name Trichodorinae.^[11] With Siddiqi's subgenera not accepted by all authorities,^[12] his elevation of these subgenera to genus level in 1980^[13][14] was followed by even fewer,^[15] but now is finding supports in molecular systematics.

Phylogenetics

In the case of Nanidorus, phylogenetic analysis has supported its recognition as a separate genus, although clustering with Trichodorus rather than its parent Paratrichodorus.^[15][16]

Genera

There were few species recognised before the economic importance of the family was recognised, and in 1957 there were only 12, but this increased rapidly. In addition further genera than the original Trichodorus (1913) and Paratrichodorus (1974) were created in the 1970s, and another genus in 2002.^[17]

There are now about 100 species divided into five to six genera.^[18][19] Duarte et al. (2010) list 102 species.^[15]

• Allotrichodorus Rodriguez-M, Sher and Siddiqi, 1978^[20] (6 species)
• Ecuadorus Siddiqi, 2002 (2 species)
• Monotrichodorus Andrassy, 1976^[21] (4 species)
• Nanidorus Siddiqi, 1974^[10]
• Paratrichodorus Siddiqi, 1974^[10] (34 species)
• Trichodorus Cobb, 1913^[22] (54 species)

The two largest genera have didelphic females (two genital tracts), and are distributed worldwide. In the contrast the three small genera, have females that are monodelphic-prodelphic (single tract) and are native to Central America and the northern part of South America.

Etymology

Trichodoridae comes from the Greek trichos (a hair) and dory (a spear).^[4] The name "stubby-root" comes from the effect of the nematodes on the root system which appears "stubby" or stunted.^[23][5]