as recognized by larval cytology and morphology
|Analysis of the karyotype of the polytene chromosomes in the fourth instar larvae has indicated the presence of a much larger Chironomus fauna than is listed in the revision of Townes (1945) or the Nearctic catalog (Oliver & Dillon, 1990). |
This list gives some information on the morphology, karyotype and distribution of about 108 species that have been recognized, but it should be noted that even this is not exhaustive as available material includes a number of specimens that do not easily fit even this expanded list.
In many cases the assigned names result from unpublished studies with the late Jim Sublette, and without the assistance of Jim, and of Wolfgang Wülker, this list would not have reached even the present degree of development.
There is also a listing of species by the Country, State or Province in which they have been recorded:
SPECIES SORTED BY LOCALITY
In these listings a couple of species are listed as "Hudson Bay Territory" in the absence of better information on the site of collection. Hudson Bay Territory existed from the 17th to 19th centuries and included the northern parts of Quebec and Ontario, all of Manitoba, and parts of Saskatchewan, Alberta, Nunavut Territory, Minnesota and North Dakota.
The initial samples of many of the provisional species were collected during my tenure of a Canadian National Research Council Post-Doctoral Fellowship at the then Entomological Research Institute, Ottawa, Canada in 1966-67. Consequently most of the adults or rearings of these species are in the collection of the Canadian National Insect Collection at the Biosystematics Research Institute. Subsequent material was supported by research funds from my friend and colleague James E. Sublette, some on a New Mexico Energy Institute Grant. The rearings from this material are mostly in the Sublette Collection in the Museum of the University of Minnesota. Further funding came from The University of Melbourne, during periods of study leave, and from a grant to Professor Stephen Case at the University of Missippi. Numerous other people have assisted with material and advice, notably Professor Dr. Wolfgang F. Wülker, Dr. Malcolm G. Butler, Professr Iya. I. Kiknadze and her group at Novosibirsk, Professor Peter S. Cranston and Dr. Martin Spies. I express my thanks to all those who have assisted with the work and ideas included in the compilation.
The broad diagnosis of Chironomus used here reflects the fact that at the time this study was begun, the nature of Einfeldia was quite unclear, and that there was a broad overlap of characters with those of Chironomus. While many aspects have been clarified, it is still not agreed that Benthalia, as used here, should be recognized as distinct from Chironomus. The subgenus Camptochironomus is not recognized here, in line with the decision of Townes (1945, p. 116). The subgenus was defined only by the enlarged genitalia of the male, but that is a common response to the adoption of mating on the substrate, and cytological and morphological studies indicate that this has occurred independently in unrelated species.
All species included in Tendipes (Tendipes) by Townes (1945) are noted, including a species of Kiefferulus and two species of Goeldichironomus (note there are other species of Goeldichironomus or Kiefferulus in the U.S.A., but they were not included in the subgenus Tendipes by Townes, or have not been included in Chironomus at any stage).SVo type of adult males
For larvae, reference is made to the mentum and mandible types originally devised by Webb & Scholl (1985), Vallenduuk & Moller Pillot (1997) and Proulx et al. (2013). These classifications were made for relatively small numbers of species, but with the much larger number of species, such as in the North American fauna, they do not cover all the variability seen in these characters and so further modification has been necessary.
As well Proulx et al. (2013) proposed four categories for the PE and a ventromental character is introduced.
Ventromental plate ratio (VMR) - ratio of the width of the marginal region of ventromentum (usually seen as a granular band under light microscopy) (a in figure below) to the distance from the anterior margin to the base of the striae (b in figure below).
The mandible type is defined by the degree of darkening and separation of the 3rd inner tooth:
Tooth coloration may be more independent of the degree of separation than recognized in Europe or by Proulx et al. 2013.
Pecten epipharyngis -
Proulx et al. (2013) recognised 4 types of PE in North American species. These are useful if the teeth are not worn down, as they often are in older larvae.
Type A - fine sharp rather uniform teeth.
Relationship on frontoclypeus of distance between antennal bases and distance between S4 setae
This character gives some indication of the shape of the anterior region of the FA: the amount and extent of the narrowing from the anterior end near the antennal bases, and where the S4 setae are in relation to the broadening of the clypeus. Where the anterior narrowing continues almost to the S4 setae the distance between antennal bases will be greater; if the narrowing is only near the antennal bases and the width remains approximately the same until near the S4 setae the distances will be about equal; while if narrowing is quite short and then begins to widen up to the maximum width, the distance between the S4 setae will be greater.
Note that this only an approximate measure of these relationships as other features, such as the relative increase in width of the frontoclypeus at its widest point, will also affect the relationship.
It should be noted that many of the larval characters referred to in the following descriptions can be quite variable. General size and ventral, lateral and anal tubules can be affected by environmental conditions, as well as by genetic variability. Appearance of mouth parts is also affected by wear: for example a worn type III central trifid tooth can appear to be type II. Genetic variation can also apply to these characters. Consequently, identification may need to be based on agreement of the majority of characters, particularly those that are least variable.
This is why identification of larvae on the basis of morphological characters is so difficult.
(includes the modified variants due to fusion of arm G):
C. species algonquian (sp. g)
C. species Obatanga (sp. 4z)
C. species Apple Valley of Wülker (sp. 3b)
C. species Le1 of Kiknadze et al. (sp. 3x)
C. species NAII of Proulx et al. (sp. 4t)
C. species NAIII of Proulx et al. (C. c.f. venustus) (sp. 4u)
C. species TE11 (sp. 4y)
C. decorus- or riparius-group: sp. 3l
C. decorus-group: sp. z; (see also main listing under thummi-cytocomplex)
C. acerbiphilus Tokunaga (sp. 4j)
C. striatipennis Kieffer (sp. 4b) (was C. strenzkei Fittkau)
C. sp. 1TE (sp. 5c)
camptochironomus-cytocomplex:C. dilutus Shobanov et al. (sp. t)
Species with unknown cytology:C. atritibia Malloch (sp. 4c)
C. vockerothi Rasmussen (sp. 3w)
C. species "Florida" Epler (sp. 4w)
Other names in the literature:C. n. sp. A of Hilsenhoff & Narf (1968) - not identified.
BOLD species cf.saxatilis (see C. sp. 1TE
C. pseudomendax(?) (sp. 4i)
C. storai (sp. 5a)
Subgenus ChaetolabisChaetolabis is normally considered a subgenus of Chironomus, but Yamamoto (1987) considers it should have full generic status.
Genus Einfeldia (s.l.)
Included in Tendipes (s.s.) by Townes (1945)