C. senegalense subgroup (= C. senegalense group s. str.)

C. imbricatum subgroup

Our study shows the following:

1. Termination (apex) of the aedeagus. We have found no difference in shape of the apex among species or subspecies within the same group, the shape is distinct only among species belonging to different groups. The apex of C. imbricatum (narrower and sharper, Plate 3: Figs 1–2. Plate 4: Fig. 6) differs from those in all species of the C. senegalense group (more blunt apex, Plate 3: Fig. 3. Plate 4: Figs 1–5). The apex in Jeannel’s holotype of C. aethiops corresponds to that in the C. imbricatum group (Plate 3), which does not support the opinion of Bruschi (2013) that C. aethiops is a synonym of C. scabrosum roeschkei.

2. Shape of inflated endophalus. We have not found an apparent difference either among species or subspecies belonging to the same group, or among species belonging to different groups (Plate 4: Figs 1–5). This result does not support the opinion that shape of the endophalus can be used to indicate assignments to to species or species groups.

3. Morphometric parameters.

A. Total length including mandibles (TL). In three measured holotypes (or lectotypes) are the values within the minimum and maximum intervals found in corresponding populations and sexes, whereas in the male holotype of C. aethiops the value is outside of the interval. The TL value in the C. aethiops holotype is closest to the values found in males of C. i. hottentotum, and lies within the interval found in females of that subspecies (all types are males, see Table 1a, Table 2). This fact supports our opinion that the holotype of C. aethiops is an extremely large male of C. i. hottentotum.

B. Maximum pronotal width to maximum head width including eyes ratio (WP/WH). The WP/WH in two measured holotypes (or lectotypes) is within the minimum and maximum intervals found in the pertinent populations and sexes. In the third taxon the WP/WH value of the holotype is outside of the interval in both sexes. In the holotype of C. aethiops is the WP/WH value within the interval found in the corresponding sex (males) of C. s. roeschkei and also within the interval found in C. i. hottentotum females. Overall the WP/WH values found in the measured taxa is very variable in both species and sexes (Table 1b, Table 2), and in our opinion thus cannot be used as a criterion in species-level taxonomy.

C.Maximum pronotal width to its maximum length ratio (WP/LP). The WP/LP value in two measured holotypes (or lectotypes) is with exception of males of C. s. scabrosum within the minimum and maximum intervals found in the pertinent populations and sexes. In the holotype of C. aethiops is the WP/WH value within the interval found in all compared species of both sexes. Overall the WP/LP values found in the measured taxa are quite non-specific in both species and sexes (Table 1c, Table 2), and in our opinion thus cannot be used as a criterion in species-level taxonomy.

D. Maximum elytral length to its maximum width ratio (LE/WE). The WP/LP value in two measured holotypes (or lectotypes) is in both subspecies of C. scabrosum within the minimum and maximum intervals found in the pertinent populations and sexes. In both sexes of C. i. hottentotum the value is outside the interval. In the holotype of C. aethiops the value is within the interval found in both subspecies of C. scabrosum. Overall the WP/LP values found in the measured taxa can be regarded as variable, namely in C. i. hottentotum. In our opinion they cannot be used as a criterion in species-level taxonomy (Table 1d, Table 2).

The above data lead us to conclude that there are no convincing morphological differences between C. scabrosum scabrosum and C. scabrosum roeschkei. The only exception may possibly be the somewhat higher WP/LP ratio (Table 2) and lighter coppery coloration in most specimens of C. s. roeschkei. Since specimens of both taxa have never been found together, we assume that they belong to allopatric populations of one species that have yet to reach the state of full speciation. Therefore, we lower the status of C. roeschkei (sensu Bruchi 2013) to a subspecies of C. scabrosum. Calosoma scabrosum roeschkei occupies mainly the southern part of distribution of the species. The present data show the north – south distribution of both subspecies to have a virtually disjunct character (Map 1). But it is in our opinion important to realize that in no area have the described subspecies been found to occur together. It is therefore likely that the northern Sudan – Ethiopia borderland will continue to produce C. s. roeschkei. The describer (Breuning 1927: 186) of Calosoma scabrosum roeschkei wrote: [“This form (roeschkei) is due to its more robust head, less bulging eyes, wider, toward base more right-angled pronotum with more rounded hind angles, shallower basal pits, somewhat flatter, at shoulders broader and terminally more abruptly slanted elytra and dark to brownish bronze dorsal coloration with light brown, coppery-rimmed margins and foveae in primary intervals so conspicuous that I originally intended to describe it as a separate species. However, some individuals of this form (roeschkei) are clearly transitional to the typical form (scabrosum), with coloration remaining as the only constant character. Differences (of separate populations) from the nominotypical form show step-like transitions, for which reason I presently regard C. roeschkei as a subspecies of C. scabrosum” (original in German)].

Jeannel (1940: 128) did not see Breuning’s subspecies but treated it as a variety and remarked: [“Breuning’s variety roeschkei rather appears to be another (separate) species closely related to C. scabrosum]”; he did not further comment on the taxon and placed specimens corresponding to Breuning’s description among African populations of “C. orientale” (Jeannel 1940: 128). In this connection, Jeannel and subsequent authors such as Rougemont (1976: 247) and Vigna Taglianti and Bruschi (1986: 21) solved taxonomic uncertainties by incorrect determination of specimens from eastern Africa as C. squamigerum Chaudoir, 1869 (Häckel 2012: 57.). The holotype of C. squamigerum is from Bengal (today either Bangladesh or West Bengal in India) and other specimens of the type series are from Coimbatore in the vicinity of Madras (today Tamilnadu State in southern India). The name C. squamigerum was therefore synonymized with C. orientale (Jeannel 1940: 128).

Jeannel nevertheless realized that African populations identified as C. orientale (=squamigerum) most likely belong to another species, coined for them a new taxon, Ctenosta (s. str.) aethiops Jeannel, 1940, and included in the distribution of this taxon also populations corresponding to Breuning’s C. s. roeschkei (“Diré Daoua”, Jeannel 1940: 128). The only exception was a population from Eritrea (“Tessenei” 1940: 129), which he continued regarding as C. orientale. In the description of C. aethiops Jeannel (1940: 127–128) wrote: [“if we regard C. aethiops with its gular and labial setae as belonging to the genus Caminara, we can see that in reality it is a transitional species combining characters of Caminara and Ctenosta, an important species attesting to its assignment to the genus Ctenosta, which differs by reduction of the said setae and the type of sculpture placing it near the Castrida-Caminara lineage. The male mesotibiae have the setal brush prolonged as in Caminara and similar to that present in Ctenosta. The ventral side of the fourth male protarsomere is smooth]”.

Evident from Jeannel’s text are the difficulties he had in placing the new species in his system and in defining the “genera”. More recently some authors (Culot 1990, Bousquet et al. 2003, Bruschi 2013) regarded the genera as subgenera, but in our opinion Jeannel’s criteria do not allow to distinguish them. For instance Bruschi in the key does not adhere to Jeannel’s criteria (setae, elytral microsculpture) and originally separates Caminara from Ctenosta on the hind pronotal angles. In the key he (2013: 29) states: “13(14) always perceptible hind angles of pronotum – Caminara/Campalita; 14(13) very small and pointed hind angles of pronotum, in some cases quite obliterated”. In our opinion Jeannel’s genera are not valid, which is supported also by their discord with results of DNA analyses. With only one exception, all the subgenera were synonymized with the genus Calosoma s. str. (Häckel 2012: 56, 2013: 12). Jeannel’s difficulties in separating the “genera” Ctenosta and Caminara (according to us two close species groups of the genus Calosoma) reflect the confused composition of the type series of his C. aethiops. Without examination of Jeannel’s holotype of C. aethiops, most subsequent authors regarded all African populations similar to C. scabrosum, with golden bronze coloration, as C. (Ctenosta) aethiops (Vigna Taglianti and Bruschi 1986: 21, Culot 1990: 9, Lorenz 2005: 68).

Only Bruschi, first on the internet and later in print (2013: Plate 17: Figs 8, 9), published photos of the holotypes of C. scabrosum roeschkei (Tanzania: Usambara) and C. aethiops (Niger: Azbin). The holotype of C. s. roeschkei (Usambara, see Map 1) clearly is a species belonging to the C. senegalense group, and we concur with Bruschi that in compliance with the priority principle the taxon must be ascribed to Breuning (the name C. s. roeschkei has priority over C. aethiops, if the two are the same species).

However, in our opinion the specimen from Azbin (Jeannel’s holotype of C. aethiops) looks different and does not belong to the C. senegalense group (=Jeannel’s genus Ctenosta). Our comparisons of types and their aedeagi show that the holotype of C. aethiops corresponds in shape, size and sculpture of the elytra, shape of the legs, and termination of the aedeagus to C. imbricatum hottentotum Chaudoir, 1852. It belongs to another group (C. maderae group, C. imbricatum subgroup sensu Häckel, 2013: =Jeannel’s genus Caminara), which partially overlaps the distribution of the C. senegalense group. Our conclusions are based chiefly on the different aedeagal morphology unequivocally shown by the photos (Plate 3, Figs 1, 2 versus Fig. 3). Futher documentation of morphological characters is not needed.

Calosoma imbricatum sensu lato is by a number of authors understood as a species with an extremely wide distribution reaching from Canary and Cape Verde Islands through the African Sahel belt, subsaharan Africa, Arabia, Iran and Pakistan to India and Bagladesh (Breuning 1927: 221–223, Jeannel 1940: 104–106, Mandl 1970: 61–63, see Map 2). The cited authors identify southern African populations of C. imbricatum as the subspecies C. i. hottentotum, whose holotype comes from the Cape province (Chaudoir 1852: 99). Calosoma imbricatum hottentotum is usually regarded as cofined to southern Africa, and Mandl (1970: 61, 63) even named another subspecies, C. i. linnavourii, for populations from eastern Africa (northern Kenya, Somalia), which is a transitional form differing from the northern (Sahel-Arabian) nominotypical form (C. i. imbricatum) by wider pronotum. Populations from southern Kenya and northern Tanzania with more lighter coppery coloration approaching rather the southern African populations (C. i. hottentotum). Jeannel (1940: 105) is the only author who regarded also the Kenya population as C. i. hottentotum. Mandl (1970: 63) commented these occurrences as “Wahrnscheinlich gehören die folgende Orte zu dieser Subspecies [C. i. linnavourii]: Kenya Sultan Hamid zwischen Voi und Nairobi, die Jeannel für hottentottum angibt”, and Bruschi (2013) countered: „It seems that, contrary to the opinions of Mandl (1970: 61) that attributed this citation to his C imbricatumlinnavourii, Jeannel is right since in south western Kenya C imbricatumhottentotum is really present“. In our opinion it is evident that the northern limit of C. i. hottentotum is vague and hosts a number of forms transitional to the nominotypical C. i. imbricatum. It is therefore possible that Jeannel’s type of C. aethiops from Azbin (today northern Niger) belongs to one of the transitional populations and the locality is in fact correct (see Map 2). In our opinion Jeannel‘s type series of C. aethiops contains the holotype that we regard as Calosoma imbricatum (most likely the subspecies hottentotum) and specimens from other populations belonging to some of the subspecies of C. scabrosum, mostly to C. s. roeschkei.

Comparison of the types of C. s. scabrosum and C. s. roeschkei in our opinion also confirms the original Breuning’s idea of one species with two terminal forms and a number of transitional forms between them (Plate 1: Figs 1–2). Another taxonomical inaccuracy was caused by Häckel et al. (2005: 2), who believed that populations newly discovered on the Arabian peninsula (Oman, Yemen, see Map 1) represent a different species (C. jakli, Plate 2. Fig. 2). Eventually, after comparison with the type of C. s. scabrosum it became clear that the Arabian specimens agree with the type (Häckel et al. 2010: 11), and today they are included in the distribution of the nominotypical subspecies C. scabrosum s. str. (Müller 1977, Häckel 2012: 57).

Below we present morphometric tables comparing populations of C. s. roeschkei (hitherto labeled as C. aethiops) with specimens of C. s. scabrosum the Horn of Africa (Djibouti) and the Arabian peninsula (Oman, Yemen). The tables also compare the noted populations of C. scabrosum with specimens of C. i. hottentotum from southern and eastern Africa and C. i. imbricatum from Afrotropical Region. In this connection we consider it important that no known locality has produced sympatrically living C. s. scabrosum and C. s. roeschkei (see Map 1). However, at at least one locality (Kenya: North-Eastern Province, El Wak, see Map 1) has produced C. scabrosum (ssp. roeschkei) together with C. imbricatum (ssp. hottentotum) and another species of the C. senegalense group (C. strandi Breuning). Our conclusion therefore is that Breuning’s (1928: 185) original idea is valid, and consequently we demote C. roeschkei sensu Bruschi (2013: 129) to a subspecies of C. scabrosum.

The subgeneric placement of C. imbricatum, C. in the subgenus Calosoma follows the recently proposed classification supported by results of DNA analyses (Su et al. 2005, Häckel 2012, 2013).