Lipurometriocnemus, Saether, 1981

Epler, John H., 2017, AN ANNOTATED PRELIMINARY LIST OF THE CHIRONOMIDAE (DIPTERA) OF ZURQUÍ, COSTA RICA Abstract Introduction, CHIRONOMUS Journal of Chironomidae Research 30 (30), pp. 4-18 : 6-7

Lipurometriocnemus

- Four species were collected, three of them undescribed. Lipurometriocnemus was first described from the British West Indies by Saether (1981), with L. glabalus as the sole species. Saether (1982) then described L. vixlobatus from South Carolina, USA. The two species were supposedly separated by the absence of setae on R 1, a weak inferior volsella and a “slight hump on tergite IX representing a reduced anal point” in L. vixlobatus . Cranston & Oliver (1988) reported L. vixlobatus from the Yukon Territory of Canada, and examined paratypes of L. glabalus and a single specimen (which they thought to also represent L. glabalus ) from Braulio Carillo National Park in Costa Rica (the Zurquí site is adjacent to a portion of the huge park). They noted that the two species were difficult to separate because of variation in the supposedly diagnostic characters, but gave no reason why they assigned the Yukon specimen to vixlobatus , which following its description should lack any setae on R 1, instead of assigning it to L. glabalus . I noted such variation in the volsellae and “anal hump” in the Zurquí material I’ve designated as L. glabalus ; there was variation in the length/ breadth of the gonostylus but much appeared due to the viewing angle. I saw no specimens in which R 1 was devoid of setae and considered all material I put in this group to be L. glabalus (63 specimens).

My L. sp. ZUR–1(eight specimens) has genitalia similar to those of L. glabalus but has a very low AR (~0.32–0.58) compared to what is being called L. glabalus today (following Cranston & Oliver 1988 and Andersen et al. 2016). In Saether’s (1981) original description of L. glabalus , all of the type material lacked antennae, but it is now apparently assumed that the species has an AR similar to that of L. vixlobatus – around 1.60–1.75. Zurquí material of L. glabalus had ARs> 1.70.

My L. sp. ZUR–2 (36 specimens) has an AR around 1.76–1.85 and genitalia very similar to those of L. glabalus , except the proximal portion of the gonostylus bears a hump that separates it from that of L. glabalus . Further work (i.e., measurements of other body parts, etc.) may show this taxon may also belong with L. glabalus .

My L. sp. ZUR–3 (two specimens) has an AR of about 1.0 or less and has a distinctively pronounced inferior volsella. Andersen et al. (2016) described two new Lipurometriocnemus species from Brazil and provided a key for the known species. Their L. biancae has a pronounced inferior volsella, but not the same as L. sp. ZUR–3, and an AR of 1.29-1.45. Their L. amazonicus (AR 1.23–1.45) is very similar to L. glabalus , but has fewer dorsocentral setae.