| Title | Corrections and Additions to Descriptions of Some Species of the Subgenus Orthocladius s. str. (Diptera, Chironomidae, Orthocladiinae) |
| Abstract | The larvae of some species of the subgenus Orthocladius s. str. (Diptera, Chironomidae) are here described for the first time with corrections and additions to the descriptions of adult males and pupal exuviae. The identification of larvae is generally not possible without association with pupal exuviae and/or adult males, so the descriptions here are based only on reared material or on pupae with the associated larval exuviae. Usually, Chironomidae larvae can be separated on the basis of morphometric characters, the most discriminant ones are: (1) the ratio between the width of median tooth of mentum (Dm) and the width of the first lateral tooth (Dl) = mental ratio (DmDl), (2) the ratio between the length of the first antennal segment (A1) and the combined length of segments 2-5 (A2-5) = antennal ratio (AR). The shape of mandible, maxilla, and other body parts are almost identical in all the species considered in this study. The larva of Orthocladius (Symposiocladius) lignicola is very characteristic and can be separated by the shape of mentum and the larvae of all the known species of Symposiocladius are characterized by the presence of large Lauterborn organs on antennae and of tufts of setae on abdominal segments. The larvae of Orthocladius (Orthocladius) oblidens and Orthocladius (Orthocladius) rhyacobius can be distinguished from other species basing on their large Dm and to each other by AR. A principal component analysis was carried out using 5 characters: (1) Dm, (2) Dl, (3) length of A1, (4) width of A1 (A1W), (5) combined length of segments 2-5 (A2-5). The most discriminant characters were Dm and A1, confirming that DmDl and AR can be used to separate species at larval stage, but the large superposition of morphometric characters in different species confirms that association with pupal exuviae is in any case needed to identify larvae. In future perspective, the development of reference DNA barcodes from specimens identified by specialists is recommended since possibly the best tool for larvae identification, but association of barcodes with morphotypes is in any case fundamental. |
| Source | Insects 13 (1), pp. 51 |
| Keywords | ChironomidsMidgesMorphometryPrincipal component analysisTaxonomy |
| Journal | Insects |
| Editor | Molecular Diversity Preservation International, Basel, |
| Year | 2022 |
| Type | Articolo in rivista |
| DOI | 10.3390/insects13010051 |
| Authors | Rossaro, Bruno; Marziali, Laura; Magoga, Giulia; Montagna, Matteo; Boggero, Angela |
| Text | 462408 2022 10.3390/insects13010051 Scopus 2 s2.0 85122198482 Chironomids Midges Morphometry Principal component analysis Taxonomy Corrections and Additions to Descriptions of Some Species of the Subgenus Orthocladius s. str. Diptera, Chironomidae, Orthocladiinae Rossaro, Bruno; Marziali, Laura; Magoga, Giulia; Montagna, Matteo; Boggero, Angela Consiglio Nazionale delle Ricerche Istituto di Ricerca sulle Acque; Universita degli Studi di Milano The larvae of some species of the subgenus Orthocladius s. str. Diptera, Chironomidae are here described for the first time with corrections and additions to the descriptions of adult males and pupal exuviae. The identification of larvae is generally not possible without association with pupal exuviae and/or adult males, so the descriptions here are based only on reared material or on pupae with the associated larval exuviae. Usually, Chironomidae larvae can be separated on the basis of morphometric characters, the most discriminant ones are 1 the ratio between the width of median tooth of mentum Dm and the width of the first lateral tooth Dl = mental ratio DmDl , 2 the ratio between the length of the first antennal segment A1 and the combined length of segments 2 5 A2 5 = antennal ratio AR . The shape of mandible, maxilla, and other body parts are almost identical in all the species considered in this study. The larva of Orthocladius Symposiocladius lignicola is very characteristic and can be separated by the shape of mentum and the larvae of all the known species of Symposiocladius are characterized by the presence of large Lauterborn organs on antennae and of tufts of setae on abdominal segments. The larvae of Orthocladius Orthocladius oblidens and Orthocladius Orthocladius rhyacobius can be distinguished from other species basing on their large Dm and to each other by AR. A principal component analysis was carried out using 5 characters 1 Dm, 2 Dl, 3 length of A1, 4 width of A1 A1W , 5 combined length of segments 2 5 A2 5 . The most discriminant characters were Dm and A1, confirming that DmDl and AR can be used to separate species at larval stage, but the large superposition of morphometric characters in different species confirms that association with pupal exuviae is in any case needed to identify larvae. In future perspective, the development of reference DNA barcodes from specimens identified by specialists is recommended since possibly the best tool for larvae identification, but association of barcodes with morphotypes is in any case fundamental. 13 Published version http //www.scopus.com/record/display.url eid=2 s2.0 85122198482 origin=inward Articolo 2022_Orthoclaidus s str_Rossaro etal.pdf Articolo in rivista Molecular Diversity Preservation International 2075 4450 Insects Insects Insects Insects. angela.boggero BOGGERO ANGELA laura.marziali MARZIALI LAURA |
