First fossil Litoleptis (Diptera: Spaniidae) from the Lower Cretaceous amber of San Just (Teruel Province, Spain)

Abstract

In this paper Litoleptis fossilis sp. nov. a new fossil species belonging to the family Spaniidae (Diptera) is described. This is the first time the genus Litoleptis has been described from the fossil record. A comparison with extant species of Litoleptis and other fossil rhagionoids is done. The fossil is also compared to not closely related Diptera but having convergent wing venation. Palaeoecological and palaeobiogeographical comments are provided.

First Tropical American Species of the “Relict” GenusLitoleptis,and Relationships in Spaniinae (Diptera: Rhagionidae)

“…Litoleptis, including fossilis: 24. Tibial spurs lost (Chillcott, 1963), though hind tibial spur apparently present and min¬ ute in L. fossilis (Arillo et al 2009). This needs to be carefully checked in the fossil since hind tibial spurs do not occur in any living Litoleptis nor in the closely related genera Spania and Spaniopsis, and small spurs (i.e., articulating in the intersegmental membrane) are sometimes difficult to discern even in modern specimens.…”

“…1, table 1), L. chilensis Hennig from Chile, and I. alaskensis Chillcott from northwest Alaska, known from only one and two specimens respec¬ tively. Such disjunction and geological age has led some authors to regard the distribution of Litoleptis as relict, the result of extensive extinction (Arillo et al, 2009;Saigusa, 2006). The oldest spaniine is Litoleptis fossilis in San Just amber from the Escucha Formation of Teruel Province, Spain, -105 mya (Arillo et al, 2009), discussed below.…”

“…sp." Nepal Nagatomi, 1982.fossilis San Just, Spain [amber] Arillo et al, 2009 * Near Point Hope, Alaska, according to Kerr (2010).…”

“…The labrum of L. tico is minute and barely sclerotized; in L. japonica it is slender and shaped like a chemistry spatula. Arillo et al (2009) indicated that the holotype of L. fossilis was a female, but based on the large, "nearly holoptic" eyes, this specimen is almost certainly a male. Those authors may have been misled by the small, obscure male genitalia of the specimen, typical of Litoleptis in general.…”

“…Determining whether these are functional pseudotracheae will prob¬ ably require SEM, but these structures should probably be best described as highly reduced, which seems to be a reliable synapomorphy of Litoleptis. Arillo et al (2009) did not mention the presence/absence of pseudotracheae in L. fossilis (they probably are too obscure), but I am assum¬ ing that they are developed and functional, given the long proboscis. 30.…”