Drosophila funebris (Fabricius, 1787)

Grimaldi, David A., 2022, The Drosophila funebris Species Group in North America (Diptera: Drosophilidae), American Museum Novitates 2022 (3988), pp. 1-28 : 3-4

THE DROSOPHILA FUNEBRIS SPECIES GROUP

Drosophila funebris group: Sturtevant, 1942: 31 (diagnosis, classification); Patterson and Stone, 1952; Bächli et al., 2004.

DIAGNOSIS: Species with dark brownish to red-brown thorax and head; abdominal coloration dimorphic (tergites in males with more extensive, darker pigmentation). Male: Epandrium and cerci completely lacking microtrichia; ventral epandrial lobe very small, bearing several small, stout setae (these short and thornlike in Old World species; slender, spinelike in New World species); male cerci with stout, heavy spines on ventral portion (most of the mesal margin in funebris ).

IMMATURES AND BREEDING SITES: Eggs with four fine filaments (known for limpiensis , macrospina , multispina , subfunebris , and trispina ). Larval stages and puparia described for D. funebris and D. multispina ( Okada, 1968) , and the puparia described for D. macrospina and D. limpiensis (Patterson, 1943) . Species of the funebris group have been caught at decaying fruits and in vinegar traps, at sap fluxes, on macrofungi, usually in forested habitats ( Werner et al., 2020a, 2020b; Miller et al., 2017; see individual species, below).

MATING BEHAVIOR: Studied by Spieth (1952) for five of the North American species ( Drosophila funebris, limpiensis , macrospina , subfunebris , and trispina ) and by Ewing (1979) for all of these except trispina but including the Old World species multispina Okada. Spieth (1952) stated that courtship and copulation among species “is relatively uniform and conforms to the basic pattern found in the subgenus Drosophila ,” although courtship is “reminiscent” of the quinaria group and male aggressiveness to that in the virilis group. Ewing (1979) studied the male courtship songs (see below, under limpiensis ).

SPECIES INCLUDED:

altukhovi Imasheva et al., 1994 : Daghestan. Type locality (TL): Makhachkala, Republic of Daghestan .

funebris ( Fabricius, 1787) : worldwide (originally Palearctic). TL: Copenhagen, Denmark.

limpiensis Mainland, 1941 : southwestern North America. TL: Limpia Canyon, Texas.

multispina Okada, 1956 : China, Far East Russia, India, Japan. TL: Sapporo, Hokkaido, Japan.

macrospina Stalker and Spencer, 1939 : eastern North America. Neotype locality: New

Orleans, Louisiana.

pentaspina Parshad and Duggal, 1966 : Jammu and Kashmir, India. TL: Srinigar, Kashmir

Valley, India.

subfunebris Stalker and Spencer, 1939 : California, United States. Neotype locality: Pasadena, California.

trispina Wheeler, 1949 : California, United States. TL: near Earp, California.

It is interesting that half the species are poorly known, presumably localized species, while Drosophila funebris is a widespread invasive. Drosophila macrospina, limpiensis , and multispina have larger distributions than the four rare species that are known just from their type localities. Drosophila trispina and subfunebris are among the rarest drosophilids in North America. Okada (1956) originally included Drosophila maculinotata in the funebris group because of the spines on the cercus, but this species is certainly not within this group based on the structure of the spermathecae, female and male internal reproductive organs; deep cheeks, and various other features. Additional species in the group will probably be found in southern China and the Himalayan region; it is unlikely that new species will be found in North America.

The four species native to the Palearctic can morphologically be defined as a monophyletic group based on the short, thornlike setae on the ventral epandrial lobe in the male ( Bächli et al., 2004; Imasheva et al., 1994; Okada, 1956; Parshad and Duggal, 1966). The native Nearctic species all have the derived features of serrate preapical lateral lobes on the aedeagus and a very distinctive pair of serrate apical lobes that articulate with the apex of the aedeagus, as described herein. Thus, there appears to be two lineages in the species group, one Palearctic and another Nearctic, each with four species.

RELATIONSHIPS WITHIN DROSOPHILA: Molecular and morphological evidence agrees that the funebris group is within the tripunctata radiation sensu Throckmorton (1975), although Throckmorton indicated a relatively isolated position for funebris within the subgenus Drosophila . Morphological features supporting placement in the “tripunctata radiation” are the following: Internally, male ejaculatory bulb with a pair of diverticula, vas deferens with a common stem; and female with ventral receptacle highly coiled ( Okada, 1956; Throckmorton, 1962). Externally: anterior reclinate orbital seta between the proclinate and posterior reclinate orbital setae (vs. lateral to proclinate or nearly so); two strong pairs of vibrissae; microtrichia reduced to entirely lost on epandrium and cerci.

There is molecular disagreement as to whether the funebris group is most closely related to the testacea group ( Robe et al., 2005; Russo et al., 2013), or to the large Holarctic quinaria group ( Robe et al., 2010; Morales-Hojas and Vierera, 2012). Finet et al.’s (2021) molecular analysis indicates that the funebris group is closely related to a group comprised of Drosophila testacea + macroptera + bizonata + histrio , and this collectively is the sister group to the quinaria group. Morphological evidence agrees best with the molecular study by Izumitani et al. (2016), that the funebris group is sister group to the rest of the tripunctata radiation after the immigrans species group. This is based on the plesiomorphic absence in the funebris and immigrans groups of a scoop-shaped “dorsal arch” between and articulating with the two ends of the posterolateral arms of the hypandrium (a distinctive structure present in the quinaria , testacea , tripunctata , and most other groups of the radiation).