Salignacicola ebboi (Perrichot, Nel et Néraudeau, 2004)

Batelka, Jan & Prokop, Jakub, 2021, The earliest beetle with mouthparts specialized for feeding on nectar is a parasitoid of mid-Cretaceous Hymenoptera, BMC Ecology and Evolution (207) 21 (1), pp. 1-12 : 7

Description of Salignacicola ebboi (Perrichot, Nel et Néraudeau, 2004) ,

a species originally placed within Macrosiagonini , cannot be compared with other ripiphorids because of absence of some important information. Several of the most prominent characters of this fossil can be, however, preliminarily reconsidered in the context of certain ripiphorid lineages or genera as follows:

1) Tibial spur formula 1-2-2. Reduction in the number of tibial spurs is common in various lineages of Ripiphoridae (see above comments for character 2 under Melanosiagon gen. nov.) and occurs also in most Macrosiagonini .

2) Antennomeres III–XI (X) in males with single long projection. Character present in all Ptilophorinae , Pelecotominae and Hemirhipidiinae , and most Ripidiinae (except for several genera with filiform antennomeres and Paleoripiphorus with biflabellate antennae). In males of Ripiphorinae antennomeres III–X (IX) always have two long rami.

3) Tread-like antennal rami. Present in some species of Macrosiagon (see above comments for character 3 under Melanosiagon gen. nov.).

4) Long hair-like sensilla on antennal rami. Similar sensilla occur in several species of Ptilophorus Dejean, 1834 inhabiting Socotra, Central Asia and USA [ 37]. Homology of this character in Salignacicola gen. nov. and the modern offshoot Ptilophorus , is unlikely.

5) Reduced wing venation. Tis character state is present in all Ripidiinae [ 38] and Ripiphorinae , but in both subfamilies the venation is quite different [ 26, 27].

6) Abdomen is 9-segmented. Ripiphoridae (except for Ripidiinae ) have a 5-segmented abdomen. Up to seven visible segments are discernible in some fossil Ripidiinae with VIIIth and IXth segment visible as internal structures [ 38]. In Salignacicola gen. nov. the reported number may be incorrect: five translucent telescopically overlapping segments would appear to be nine units. Tis character should be reinvestigated.

7) Legs long and slender with apical setal fringes on tibia and tarsomeres. Typical for Macrosiagonini (like Metoecus ), Pelecotominae and Hemirhipidiinae . In Ptilophorinae they are much shorter and stronger, in Ripidiinae distinct tibial and tarsal setal fringes are absent.

8) Long meta(tibial) spurs. Present only in Ptilophorinae and Ripiphorinae (see above comments for character 9 under Melanosiagon gen. nov.).

9) Serrate pretarsal claws. Now known in both Ripiphorinae tribes, Ptilophorinae , and South American Pelecotominae (see above comments for character 10 under Melanosiagon gen. nov.).

Salignacicola gen. nov. shares characters 1, 3, 5, 8 and 9 with Ripiphorinae as the subfamily is now understood (i.e., including Melanosiagon gen. nov.), but uniflabellate antennae (character 2) excludes Salignacicola gen. nov. from Ripiphorinae more basally or it might require (depending on the shape of the sclerites on the metathorax) redefinition of this character in this subfamily. Long hair-like sensilla on antennal rami (character 4) can be interpreted as an apomorphy of the genus, but not as synapomorphy with certain recent species of Ptilophorus bearing similar sensilla. Salignacicola gen. nov. thus, may represent a stem lineage of Ripiphorinae (retaining the uniflabellate antennae of its ancestors), which went extinct at the end of Cretaceous, but its exact phylogenetic position within the subfamily will remain unclear until the critical characters of the holotype are reinvestigated using micro-CT and redescribed in accordance with the high standard of the descriptions of most of the Ripiphoridae entrapped in very transparent Burmese amber.