Susana

Taxonomy

Family: Tenthredinidae
Family common name: common sawflies
Subfamily: Nematinae
Tribe: unplaced
Genus: Susana Rohwer & Middleton, 1932
Subgenera: none

Background

The Tenthredinidae are the most species-rich family and are found throughout the world, in all continents but Antarctica. They are known as the “common sawflies.” They can generally be recognized by a cylindrical body and long, segmented antennae. Otherwise, they come in a variety of colors, sizes, and forms (Goulet 1992).

Nematinae is the second-largest subfamily of Tenthredinidae, with over 1,250 species (Prous et al. 2014). They are most diverse in northern Eurasia and North America; only a few species occur in the Southern Hemisphere. Nematinae sawflies have a variety of feeding habits including external leaf feeding, leaf mining, and gall forming, and feed on a variety of hosts (Smith 2003b).

The Nematinae have been subject to numerous revisions in recent years. As of 2021, there are no comprehensive keys to many of the North American species of Nematinae (Prous et al. 2014). Because of changing taxonomy and extreme variability in morphology, identifying genera and species in the Nematinae may be more challenging than in other subfamilies of Tenthredindae. For this reason, knowing the host or behaviors of a specimen can be extremely helpful for identification within this subfamily.

Susana was previously placed in its own subfamily due to unusual larval characters and the lack of a prepectus in the adults (Smith 1969d, Goulet 1992). It is now included in the Nematinae, which are recognized by the clearly convergent fore wing veins M and 1m-cu (Nyman et al. 2006b). Susana is a western genus. Species are generally about 7–10 mm in length and orange and black in color. Males have somewhat broad, flattened antennae (Smith 1969d, Smith 2006c).

Diversity

There are 10 described species, all of which occur in North America (Taeger et al. 2018).

A key to all species is included in Smith 2006c.

Diagnostic characteristics

​Subfamily characters​

Genus characters

May be confused with

Susana may be confused with other genera in the subfamily Nematinae, especially Craterocercus, but can be distinguished from it and other genera that have fore wing vein 2A+3A curved upwards and vein 2r-rs present by: the absence of a prepectus, tarsal claw with short subapical tooth, and a truncate clypeus (Rohwer and Middleton 1932, Smith 1969d, Smith 2006c). Some species of Pristiphora also lack a defined prepectus, but are easily distinguished by the incomplete and straight fore wing vein 2A+3A.

Exotic pest species of concern

none

Host associations

Susana feeds on species of Cupressus (cypress), including C. macrocarpa (Monterey cypress) and C. sempervirens (Mediterranean cypress), and on species of Juniperus (juniper), including J. occidentalis (western juniper) and J. scopulorum (Rocky Mountain juniper) (Smith 2006c).

Life history

unknown

Distribution

World: The genus is known only from North America (Goulet 1992).

North America: Susana occurs west of the Rocky Mountains, as far north as British Columbia, and south to Oregon, California, Arizona, and New Mexico (Smith 2006c).

Map data from: GBIF.org (29 October 2019) GBIF Occurrence Download Susana and the Oregon State Arthropod Collection (OSAC)

Details about data used for maps can be found here.

Susana cupressi female lateral habitus; photo by J. Orr, WSDA

Susana cupressi female lateral habitus; photo by J. Orr, WSDA

Susana cupressi female dorsal habitus; photo by J. Orr, WSDA

Susana cupressi female dorsal habitus; photo by J. Orr, WSDA

Susana cupressi female face; photo by Q. Baine, WSDA

Susana cupressi female face; photo by Q. Baine, WSDA

Susana cupressi male face; photo by Q. Baine, WSDA

Susana cupressi male face; photo by Q. Baine, WSDA

Susana cupressi wings; photo by J. Orr, WSDA

Susana cupressi wings; photo by J. Orr, WSDA