Tomostethini
Genus Guides
2- Tethida
- Tomostethus(ash sawflies)
Tomostethini is a tribe of within the Tenthredinidae. Members are phytophagous, with larvae feeding on plant foliage. The tribe includes the *Tomostethus*, whose larvae are known to feed on ash trees (*Fraxinus* spp.). Sawflies in this tribe can be distinguished from related groups by a combination of morphological features including wing venation patterns and genitalia structure. are generally small to medium-sized hymenopterans with two pairs of membranous wings.
Pronunciation
How to pronounce Tomostethini: /tomoˈstɛθɪnaɪ/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Tomostethini can be distinguished from other Tenthredinidae tribes by the following combination of characters: forewing with 2A+3A complete and connected to 1A by a crossvein; hindwing with M present; and male genitalia with specific configurations of the harpe and paramere. The tribe is further characterized by a pronotum that lacks distinct lobes. These features require microscopic examination for reliable identification.
Images
Distribution
The tribe has a Holarctic distribution, with records from North America, Europe, and Asia. Specific range limits are poorly documented due to taxonomic revisions and limited survey effort.
Diet
Larvae feed on foliage of woody plants. *Tomostethus* have been documented feeding on ash (*Fraxinus* spp.).
Host Associations
- Fraxinus - larval food plant for *Tomostethus*
Life Cycle
Holometabolous development with , larval, pupal, and stages. Larvae are external leaf feeders. occurs in soil or leaf litter.
Ecological Role
Larvae function as primary consumers, processing leaf . Their feeding activity contributes to nutrient cycling in forest . can cause localized defoliation of trees.
Human Relevance
Some *Tomostethus* , particularly *Tomostethus nigritus*, are recognized as occasional pests of ornamental and forest ash trees. Larval feeding can cause aesthetic damage and, in years, significant defoliation. The tribe has no known agricultural or economic benefits.
Similar Taxa
- TenthredininiOverlaps in general and use; distinguished by wing venation details and male genitalia structure
- CroesiniSimilar size range and ; separated by pronotal structure and forewing configuration
More Details
Taxonomic history
The tribal classification within Tenthredininae has undergone revision. Tomostethini was established based on phylogenetic analysis of morphological characters, though some authors have questioned its monophyly. The *Tomostethus* was historically placed in Tenthredinini.
Research needs
Basic of most Tomostethini remains undocumented. plant records are sparse outside of *Tomostethus*. studies and larval descriptions are needed for many .