Cacomisthus Townes, 1970

Taxonomic History / Nomenclature
Cacomisthus Townes, 1970: 75. Type species: Cacomisthus niger Townes, 1970. Monobasic and original designation.
Cacomisthus is presently (April, 2015) known from a single species recorded from southern Chile, Cacomisthus niger Townes, 1970. Hosts and other biology unknown. Males are also unknown at this time.

Holotype label: Punta Arenas, Magallanes, Chile, March 11, 1962, T. Cekalovick (in AEI: American Entomological Institute).
Paratypes (in AEI): Los Robles, Magallanes, Chile, Jan. 22, 1961, T. Cekalovick. Female, 3 km. east of Las Trancas, Roble, Chile, Jan. 16, 1967, Lionel Stange.

Diagnosis and Relationships
As noted by Townes (1970), the second flagellar segment is equal to or longer than the first (Fig. 1), which differentiates at least the type species from all other members of the Pionini. Cacomisthus also has a relatively short, broad T1 lacking dorsal carinae, very short hind tibial spurs (Fig. 2), and a short, bulging, densely setose face with eyes converging ventrally. Cacomisthus keys with difficulty in Townes (1970) because the glymma and epicnemial carina characters are difficult to assess. In general appearance, it is most similar to some of the species of Rhaestus.

The type species is relative small (front wing 2.7 to 3.3 mm. long according to Townes (1970)). It is a black species with infumate wings and the apex of femora and adjacent base of tibia whitish.

1. Cacomisthus...
Clypeus punctate, densely setose (Fig. 3; with ventral margin evenly rounded, convex, the margin blunt (Fig. 4); epistomal sulcus sharply and distinctly impressed throughout; clypeus in profile weakly protruding, face more strongly so (Fig. 5). Face densely punctate but otherwise smooth (Fig. 4), very densely setose (Fig. 3); frons and vertex smooth, with a few, scattered setae; inner eye margins converging (Fig. 3). Ocelli small, diameter of lateral ocellus much shorter than distance from lateral ocellus to eye. Malar space absent. Mandible evenly curved, gradually narrowing distally; dorsal tooth narrower and shorter than ventral tooth (Fig. 4); basal, transverse impression absent. Maxillary palp a little shorter than height of head; female antenna (Fig. 6) slightly shorter than body, with first flagellomere slightly shorter than second. Hypostomal carina meeting occipital carina distinctly dorsad base of mandible; occipital carina complete. Epicnemial carina extending to or nearly to anterior margin of mesopleuron. Notaulus (Fig. 8) distinctly impressed on anterior declivity, very shallow, barely indicated dorsally (difficult to see, but varying in length on disk in the two specimens examined). Groove between propodeum and metapleuron u-shaped; broad, u-shaped groove mid-dorsally between propodeum and metanotum present though not always readily visible in lateral view because of relatively small size of the type species; pleural carina well-developed throughout; propodeal carinae variable: median and lateral longitudinal carina distinct throughout (Fig. 9), posterior transverse carina complete, anterior transverse carina complete except for median portion in material examined, but shown as completely absent in Townes (1970: 233, fig. 70), in either case, areola confluent with median basal area, petiolar area with median longitudinal carina; propodeum largely smooth, poliished, with some weakly rugose sculpture in petiolar area. Apical margin of mid tibia expanded into a distinct tooth similar to that of fore leg; apical comb on posterior side of hind tibia weakly developed; posterior hind tibial spur very short, at most 6x longer than maximum width at base; tarsal claws small and difficult to see but apparently bifid or, as suggested by Townes (1970), with a long basal tooth. Fore wing areolet absent; stigma broad (curled in Fig. 10), with Rs+2r arising from near basal 0.35. Hind wing with first abscissa of CU1 much longer than 1cu-a. T1 broadening from base to apex (Fig. 12), without dorsal carinae; basal depression at dorsal tendon attachment very shallow; dorsal-lateral carina present between spiracle and apex of T1; glymma very small, indistinct near base, presence actually needs verification, perhaps with SEM, due to rugose sculpture laterally on T1. S1 extending to spiracle; spiracle distinctly posteriorad midpoint of T1 (Fig. 11). T2 (Figs. 12, 13) with thyridium absent; laterotergites of T2 and T3 not separated by creases from median tergite; the median transverse impression across T2 noted by Townes (1970) is present in one of the two specimens examined but not in the other. Ovipositor straight in one specimen, decurved in the other (Fig. 14) thickened over basal 0.4-0.5, abruptly narrowed, needle-like apically, without dorsal, subapical notch; ovipositor sheath narrow througout. Cerci exceptionally long, about 0.35 times length of ovipositor sheath.

The description is based largely on two females in the Texas A&M University collection.

1.Cacomisthus habitus
2. Cacomisthus habitus posterior vie...
3.Cacomisthus face
4.Cacomisthus mandible
5. Cacomisthus hea...
6. Cacomisthus...
7. Cacomisthus mesoscutum...
8. Cacomisthus showing notau...
9. Cacomisthus propode...
10.Cacomisthus wings
11.Cacomisthus T1
12. Cacomisthus...
13. Cacomisth...
14. Cacomisthus ovipositor and sheath...
No referenced distribution records have been added to the database for this OTU.

There are no specimens currently determined for this OTU, or those specimens determined for this OTU are not yet mappable.

This page was assembled by Bob Wharton as part of a larger collaborative effort on the genera of Ctenopelmatinae.

This work would not have been possible without the groundwork provided by Ian Gauld’s study of the Australian and Costa Rican faunas, and we are particularly grateful for his assistance in many aspects of this study. We also thank David Wahl of the American Entomological Institute and Andy Bennett of the Canadian National Collection for extended loans of the material used for this study and particularly John Heraty for his collection of valuable material from Chile. Matt Yoder provided considerable assistance with databasing issues, and our use of PURLs ( in this regard follows the example of their use in publications by Norm Johnson. Heather Cummins, Andrea Walker, Patricia Mullins, Caitlin Nessner, Amanda Ladigo, Jacques Dubois, and Cheryl Hyde graciously assisted with image processing, formatting, and literature retrieval. This study was supported by the National Science Foundation’s PEET program under Grant No. DEB 0328922 and associated REU supplement #s DEB 0723663, 0923134, and 1026618. Page last updated April, 2015.

This material is based upon work at Texas A&M University supported by the National Science Foundation under Grant Number DEB 0328922 with REU supplements DEB 0723663, 0923134, and 1026618. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.