Homonotus niger (Marquet, 1879)

Schmid-Egger, Christian, 2018, A review of the genus Homonotus D, 1843 in the West Palaearctic region with description of a new species (Hymenoptera, Pompilidae), Linzer biologische Beiträge 50 (1), pp. 809-824 : 812-815

Homonotus niger (MARQUET, 1879), changed status, fig. 10

Ferreola nigra MARQUET, 1879: 474, female. Holotype female, Italy (Toulouse, type lost, R. Wahis pers. comm.). Synonymised with H. sanguinolentus by HAUPT (1927: 289). Changed status.

Pompilus doctor DALLA TORRE, 1897: 286. New combination and new status. Replacement name for Ferreola nigra MARQUET, 1879; nec Salius niger RADOSZKOWSKI, 1877 in Pompilus (WAHIS, 1986).

R e c o r d s: males are only listed when associcated with females: Austria: 1 female 12.viii.1993 Steiermark, Deutsch Haseldorf ( OLL). France 2 females 13.v.1971 Corsica, Calvi ( OLL). Germany, 1 female 17.vii.1996 Bavaria, Kitzingen, Military area KlosterForst ; 2 females 20.vii.2010 Schleswig Holstein, Weissenhäuser Brök ( CSE) ; 2 females 27.vi.2009 Mecklenburg Vorpommern, Mariendorf auf Rügen, 54.33N 13.68E (Jacobs); 1 female 28.vii.1998 Berlin, Blankenfelde, Köppchensee ; 1 female 22.vi.2008 Brandenburg, Uckermark, Gross Dölln, Flughafen (Saure). Italy, 1 female 11.vi.1996 Aosta Valley, Pondel 880 m NN. ( CSE) ; 1 female 1 male Triest 4.vi.1959 ( OLL). Netherlands: some specimens from different locations (Leiden). Slovakia: 1 female 26.vii.1993 Chotin ( OLL). Tschech Republic: 1 female 28.vi.2010 Boh. occ, Prunelov ; female 4.viii.2003 Miloyice OLL), Spain: 1 female viii.1933 Cercadilla, Estacion Alpina , 1500m (Leiden). 1 female 18.v.1992 Prov. Zaragoza, Pinha de Ebro ( CSE) .

D i s c u s s i o n: Homonotus species from Europa, West and Central Asia were not treated consistently in the past. R. Wahis (see Fauna Europaea, https: //fauna-eu.org/) recognized only one European species, H. sanguinolentus , whereas WOLF (1972) recognized two European species, H. sanguinolentus and E. balcanicus. In Central Asia, Wolf (pers. comm.) regarded a third species to be present, H. collaris . Species recognition in general is difficult because of different colour forms in females, and the lack of good morphological diagnostic characters.

The examination of about 200 new Homonotus specimens results in the following

conclusions:

. Three taxa of this species group are occurring in the treated area.

. Females of these taxa can be recognized by colour pattern, with some exceptions. Males of two taxa ( H. niger and H. sanguinolentus ) are not distinguishable by morphology or colour pattern with certainty.

. One taxon ( H. transcaspicus ) can be recognized by morphological characters in males and females. It is a valid species without doubt. It is characterized by form of metanotum, by colour pattern of females, and by distribution pattern. Genetic data (Schmid-Egger in prep.) support its state as valid species. For nomenclature see below.

. Both remaining taxa, H. niger and H. sanguinolentus , are only distinguishable by colour pattern of females. Some morphological characters of males (mainly in pattern of tergal pubescence, form of metanotum etc.) cannot be confirmed with certainty because not enough fresh specimens were available for exact examination. Provisional genetic data (Schmid-Egger in prep.) are not conclusive. There are two genetic clusters within specimens from Central Europe but most data were inferred from males and cannot be used for species recognition.

. Remaing nominal taxa could be clarified and are synonyms of one of the three mentioned species.

For that reason, the main question in the present study is the treatment of the two European taxa H. niger and H. sanguinolentus . Most former and present authors recognize only one species with two female colour forms. However, there is no explanation for the occurrence of this two quite different and partly sympatric forms. The forms differ also by the following characters:

. The black form ( H. niger ) occurs mainly in western and Central Europe,

eastwards to Poland ( WISNIOWSKI, 2009), and also in southern Europe.

. The red form ( H. sanguinolentus ) does not occur in the western and southwestern parts of Germany, and is rare in western Europe (e.g. it occurs in the Netherlands, H. Nieuwenhuijsen pers. comm). In Germany it is restricted to warm and dry meadows (mainly "Steppenrasen" habitats) in the eastern part of the country. It is not known from Poland ( WISNIOWSKI 2009).

. There are no transitional colour forms between both taxa. The female of H. niger is all black, without traces of red on pronotum or propodeum. The colour pattern of H. sanguinolentus females varies from an all red mesosoma to some black parts in medial mesosoma, but pronotum and propodeum is always all red.

In my opinion, the concept of two valid species is more likely than a concept of colour forms only. Generally, the change from red to black (not uncommon in Pompilidae ) passes in north-south direction (e.g. in Arachnospila, Priocnemis etc., whereas many species have black forms in south Europe), and often transition forms occur in these species. Also, distribution pattern supports the concept of two species, because both taxa have a separated distribution area with a wide overlapping area. H. niger seems to have a West or Southwest European origin, whereas H. sanguinolentus is most likely a southeastern European or Continental species, similar to H. transcaspicus .

For that reason, I treat the black form as a valid species, different from H. sanguinolentus s.str. The red form (female) clearly refers to the description of Sphex sanguinolenta FABRICIUS, 1793, and so the valid name for that taxon is consequently Homonotus sanguinolentus . The black (female) form refers to the description of Ferreola nigra MARQUET, 1879, described from Italy. The type of the latter seems to be lost (R. Wahis pers. comm.), but the description fits unambiguously to the black form of " H. sanguinolentus ". So, the black form has the valid name H. niger .

A problem remains with the males, which cannot be recognized with certainty (maybe later studies with more fresh material will confirm the below described characters, but for the moment they are not suited for a certain species recognition).

D i a g n o s i s: The female of H. niger is all black, whereas the female of H. sanguinolentus has mesosoma partly or all red. Males of both species are black and similar in colour. The species also can be distinghuished in both sexes by form and size of pubescent tergal bands. In H. niger they are less developed compared with H. sanguinolentus , and lack in males more or less. The recognition of males is not always easy, because pubescence may worn down. Smaller males of H. sanguinolentus also may lack parts of the typical pubescence. Another character is tergal structure in males. It is more shiny with some bluish shimmer and larger interspaces (as large as puncture diameter) in males of H. niger , and with a dense punctuation with partly invisible interspaces and an duller impression in H. sanguinolentus . For recognition of the similar H. transcaspicus see below.

F e m a l e: 8-11 mm. Colour: body all black. Mandible may be partly red. Tibial spurs white. Wings infuscate. Morphology: Apical clypeal margin with small median emargination, or straight, and with a median impression. Gena above as wide as length of scape, below ca. 0,3x length of scape. Pronotum 0,8x as long as wide. Scutellum apically with small impression. Metanotum with week medial impression, apically slightly triangular emarginated, with wide obtuse angle, in one species nearly flat. Longer hindtibial spur 0,75-0,9x as long as hindmetatarsus. Cubital cell III longer than cubital cell II. Tergite I apically with lateral short band of scattered white pubescence. Tergite II apically with band of white pubescence, medially widely interrupted (gap as long as shorter spur of hindtibia), as wide as 2/3 length of scape. Other morphological characters as length of gena, of cubital cells or of antennal segment are variable.

M a l e: 5-9 mm. Colour: body all black, apex of mandible with some red, tibial spurs white. Morphology: Agree in main characters with female. Tergites laterally with some brownish setae, no tergal bands of white pubescence visible. Base of tergite II with some white and very fine pubescence, barely visible and much weaker as in H. sanguinolentus . Tergal surface shiny, with a weak bluish shimmer, finely punctured with interspaces partly as large as puncture diameter or larger. Pronotum 0,7x as long as wide (measured in the middle of pronotum).

D i s t r i b u t i o n: The overall distribution of H. niger ist still unknown, because the species was confused with H. sanguinolentus , and most publications do not refer to the colour of females. The present records show a Central and West European distribution with some scattered records from Southwest Europe. The species occur eastwards to Poland and Czech Republic.