Larsia Fittkau, 1962

Cranston, Peter S., 2007, The Chironomidae Larvae Associated With The Tsunami-Impacted Waterbodies Of The Coastal Plain Of Southwestern Thailand, Raffles Bulletin of Zoology 55 (2), pp. 231-244 : 234

Larsia Fittkau

( Figs. 14–16 )

Larsia is a frequently-occuring genus especially in warm streams and rivers, but is encountered less often in tropical standing waters. Pupal evidence suggests that diversity is higher than the sole published regional record of L. albiceps ( Johannsen, 1931) whose immature stages were described by Zavrelˇ (1933) from Sumatra. Regionally, larvae were found only in dilute, unimpacted sites ranging in conductivity from 50–1570 µS. cm−1 and in dissolved solids from 23–1,570 ppm. A single pupa, from the most dilute site, has a thoracic horn ( Fig. 16 ) unlike any other found in the genus in Asia or Australia: no association with larvae from any other site can be made with any certainty. However, the larvae from this survey are not the same as those identified tentatively as L. albiceps from Australia ( Cranston, 2000) judging from slight differences in the arrangement of the cephalic setae and especially the strength of the transverse ‘creases’ of the mentum (gula and submentum) in the Thai specimens ( Fig. 15 , m, sm) compared to Australian specimens.

Figures

Figs. 13–25. Thai post-tsunami Chironomidae. Ventral head setae and pit: 13, Monopelopia sp., 14, Larsia sp. Larsia sp.: 15, mentum; 16, pupal thoracic horn. Parakiefferiella sp.: 17, mentum; 18, antenna; 19, mandible. Menta: 20, Tanytarsus formosanus; 21, Zavreliella sp. Antennae: 22, Tanytarsus formosanus; 23, Tanytarsus ‘Thai 1’; 24, Tanytarsus ‘Thai 2’; 25, Zavreliella sp. Abbreviations: LO, Lauterborn organ; m, mentum; sm, submentum; SSm,seta submenta; S9, S10, cephalic setae 9, 10; vmp, ventromental plate; VP, ventral pit.