Melaenus elegans Dejean 1831

Ball, George E. & Shpeley, Danny, 2005, Taxonomic review of the Tribe Melaenini (Coleoptera: Carabidae), with observations on morphological, ecological and chorological evolution, Zootaxa 1099 (1), pp. 1-120 : 1-120

Melaenus elegans Dejean 1831

( Figs. 9 , 10 )

Melaenus elegans Dejean 1831: 482 . TYPE MATERIAL: in Oberthür/ Chaudoir Collection (MNHP). LECTOTYPE, here designated, (sex undetermined), labeled: "elegans"; " Sénégal "; "Dumolin" [this and the preceding, handwritten on blue paper]; "Ex Musaeo/Chaudoir" [red print].—Lacordaire 1854: 167.—Péringuey 1926: 608.—Burgeon 1935: 175.

Melaenus elongatus Chaudoir 1843: 721 . TYPE MATERIAL: in Oberthür/ Chaudoir Collection (MNHP), associated with the following box label: "elongatus/ Chaud./ Kordofan/ Parrey s." LECTOTYPE, here designated, female, labeled: "type/ Parreyss"; "atramentarius/ Nobis Bohem" [both labels handwritten]; "Ex Musaeo/ Chaudoir" [red print]. NEW SYNONYMY.

Notes about type material. Dejean (1831: 482) gave two measurements for M. elegans , indicating he had at least two specimens. Chaudoir (1843:721) gave only one measurement for M. elongatus , but it is possible that he had more than one specimen. Although each of these nominal species was represented by a single specimen in the Oberthür/ Chaudoir collection, each is designated as LECTOTYPE for its respective species.

Notes about synonymy. The principal difference between the types of the two putative taxa is size (for M. elegans , the SBL is 6.56 mm; for M. elongatus , 9.38 mm). The latter is indeed large for an African Melaenus , and is euphthalmous (large­eyed, see “Geographical Variation”, below). However, that is the only difference of the few specimens noted by Chaudoir (1843: 721) and that were examined quantitatively. This difference is bridged by other specimens. So, larger size is not a basis for species recognition.

Type area. Sénégal .

Recognition. See key to melaenine taxa. This is the only African species of Melaenus .

Comparisons. A description is not required here because of the marked similarity between adults of this species and those of M. piger . The two groups overlap broadly in size and proportions, with M. elegans averaging larger in size, as indicated by values for SBL:

M. piger (N = 20) 6.19–8.19 mm, Mean 7.61 mm;

M. elegans (N = 19) 6.80–9.89 mm, Mean 7.70 mm.

Geographical variation. Eye size and surface punctation exhibit an interesting pattern. In western Africa ( Mali to Sénégal) eye size and density of head and pronotal punctation is monomorphic: eyes relatively large, and punctation moderately dense ( Fig. 9C ). In eastern Africa, these features are markedly dimorphic: most individuals that we have seen from the Sudan, Ethiopia, and Somalia are like their western counterparts, comprising a euphthalmous form ( Fig. 9C ). But some individuals, sympatric with the euphthalmous form, exhibit smaller eyes and denser punctation, and are grouped as the microphthalmous form ( Fig. 9B ). The differences are expressed as two ratios: relative eye length (OL/VW), and eye convexity (HW/PMW). Values for these ratios are presented in Table 10.

For the ratio OL/VW, values are non­overlapping for males (microphthalmous, 0.22– 0.31; euphthalmous, 033–044). For females, overlap in values overall is slight (microphthalmous, 0.24–0.33; euphthalmous 0.31–0.43), but within regions, values do not overlap.

For the ratio HW/PMW, values overall overlap broadly: for males (microphthalmous, 0.66–0.73; euphthalmous, 0.69–0.75) and for females (microphthalmous, 0.65–0.72; euphthalmous, 0.69–0.75). But on a regional basis, males of the two eye morphs of the Sudanese and Somalian samples exhibit non­overlapping values, whereas for females, only the Somalian samples exhibit non­overlapping values. For both males and females, overlap is most extensive for the Ethiopian/Eritrean samples, least for the Somalian sample, with the Sudanese sample being intermediate.

The overall pattern of variation is one of continuity, as shown by a combination of the two ratios ( Fig. 9A ). Size range, as indicated by values for SBL ( Table 10), overlaps broadly for the two morphs, but larger individuals seem to be more frequent for the euphthalmous morph.

Regarding surface punctation, overall the microphthalmous individuals exhibited more punctures on the dorsal surface of the head ( Fig. 9B ), and ventral surface of the metasternum, and medial areas of abdominal sterna III–IV. In euphthalmous individuals, the ventral surface of the metasternum was either impunctate or punctate; the medial area of abdominal sterna III–IV was either impunctate, punctate in apical half only, or punctate throughout. A few of the euphthalmous individuals exhibited more punctures on the dorsal surface of the head than some microphthalmous individuals.

In summary, morphometric dimorphism is especially marked in Somalia. In Ethiopia / Eritrea, one finds typical euphthalmous and microphthalmous individuals, but also some whose features bridge the gap between the extremes. Further, extent of surface punctation is partially correlated with eye size, but not completely. These differences may indicate specific distinction, but in view of the virtual continuity of variation among the small samples, the marked overlap in geographical range, and the absence of other features to distinguish the two morphs, we infer that they are conspecific, One might make a case for recognition of a western monomorphic subspecies, and an eastern one that is dimorphic for eye size, but such taxonomic recognition is not recommended at this time.

Habitat, habits and seasonal occurrence. This species occupies primarily the tropical deciduous forest/savannah vegetation zone (dry woodland and grassland; see Hall and Moreau 1970: xiii, Map B), but also marginally, the desert/semi desert zone ( Figs. 10 , 24 and Table 17), at altitudes between sea level and 2000 m. The "desert" record concerns a specimen from Cairo, which might have reached that locality by way of the Nile River, a more mesic route across the Sahara desert. Based on label data, we infer that the period of adult activity extends throughout the year, with records for every month. However most specimens were collected in October.

Geographical distribution ( Fig. 10 ). This species is confined to the African continent, and is probably indigenous in the Afrotropical Region.

Relationships and chorological affinities. This species is the putative adelphotaxon of M. piger , the only other known species of Melaenus . See comments under "Geographical distribution" for M. piger , above.

Material examined. Excluding types, we have seen 134 specimens from the following localities, most of which are in the Afrotropical Region . The locality records are grouped by morph (euphthalmous; and microphthalmous) .

EUPHTHALMOUS MORPH

CAMEROON: Garova, 2.X.1966, and 27.IX.1974, P. Bruneau de Miré, 2 (MNHP); Koze, Guétalé, IX.1970 P. Bruneau de Miré, 1 (MNHP); Mayo Kebi, route de Béré, 2.XI.1977, Bruneau de Miré, 1 (MNHP); Yagova, VIII.1971, Bruneau de Miré, 9 (MNHP); CHAD. Bas Chari, Fort Lamy, 1904, D.J. Decorse, 2 (MRAC); Ouadi Ouargalla=Ouadi Goumer, 18.IX.1935, 2 (MRAC). DEMOCRATIC REPUBLIC OF THE CONGO. Tanganika Dist.: Moero Ankoro, 21.VI.1930, D.R. Gerard, 1 (MRAC).

ERITREA. Setit Humera , 14.X.1973, T.J. Crowe, 6, 17 (MRAC) . ETHIOPIA. Ilubador: Gambela, XI.1972, R.O.S. Clarke, 7 (MRAC). Sidamo: 18 km NE Yavello, 1550 m, 7– 10.V.1975, R.O.S. Clarke, 6 (MRAC). District not determined: Omo Valley , I.1942, H.T.E. Jackson, 1 (MRAC); same, 2 (USNM) . GUINEA­BISSAU. Susana , 12º18'23", 16º28'28", VII.1953, Andreoletti, 2 (MRAC) . KENYA. Da Dime, al bas Narok, VIII– IX.1896, Bottego, 1 (Nègre Coll., MNHP); 750 m., III.1912, Alluaud & Jeannel, 2 (MRAC) . MALI. Dogo , 5.VIII.1950, G. Remaudiere, 1(MRAC); Goundam, XII.1954, R. Mauny, 2 (MRAC); Kogoni, X.1966, G. Schmitz, 11 (MRAC); Kouya Lac­Fati, R. Mauny, 2 (MRAC) . MAURITANIA. Bafrechie, IFAN, 15.IX–10.X.1953, A. Villiers, 1 (MRAC); Boghe , X.1968, R. Frieser, 1 (MRAC); Rosso, J.L. Amiet, 4 (MRAC) . MOZAMBIQUE. Nova Chupanga, near Chemba,1928, P. Lesne, 1 (MRAC); Nova Chupanga , XII.1928 – I.1929, J. Surcouf, 1 (MRAC); Sone, 1929, J. Surcouf, 1 (MRAC) . NIGER: Aïr, Agadez, 23.X.1953, P. Bruneau de Miré, 1 (MNHP); Temesna Irhazer , 22.I.1951, P. Bruneau de Miré, 1 (MNHP) . SÉNÉGAL. Richard Toll, IX.1948, A. Villiers, 1 (MRAC); same, XI.1967, A. Descarpentries, T. Leye, & A. Villiers, 2 (MRAC); same, at light, 8.X.1969, G. Schmitz, 1 (MRAC); St. Louis , environs, VII.1952, L. Laurent, 1 (MRAC); "Sénégal". 3 (OXUM) . SOMALIA. Afgoi, 1.VIII.1977, Olmi, 1 (MRAC); Belet Amin (Giuba), P. Basilewsky, 1 (MRAC); Giohar, 18–20.IV.1968, 1 (MRAC); Pnd. di Fungalongha , III– IV.1923, Patrizi, 1 (Nègre Coll., MNHP) . SUDAN. Blue Nile Province: Abu Hashim­ Galegu, 23–24.II.1962, Linnavuori , 1 (MRAC);; same, 14.3ºN, 5–20.X.1901, W.L.S. Loat, 1 (OXUM); Wad Medani, at light, 9–29.X.1979, F. Hieke, 4 (MRAC). Kassala Province: Kassala­Haiya, 1–3.XII.1962, Linnavuori, 3 (MRAC). Kordofan Province: 1 [holotype, M. elongatus Chd. ] (MNHP); 1 (MNHP); Kadugli, VII.1952, C. Sweeney, 1 (CASC). Upper Nile Province: Malakal, 4.VI.1927, L. Burgeon, 1 (MRAC); same, 1963, Linnavuori, 1 (MRAC); same, 5–20.I.1963, Linnavuori, 4 (MRAC) . TANZANIA. Mesal District: Longido , 1500m, 17–20.IV.1957, P. Basilewsky & N. Leleup, 3 (MRAC) .

PALAEARCTIC REGION. EGYPT: "Egypt", 1 (OXUM); Kafr Hakim, 23.X.1932, A. Alfieri, 1 (USNM); Sakkara, 9.10.1932, W. Wittmer, 2 (Antoine Coll., MNHP); Talbich, 9.X.1932, A. Alfieri, 1 (USNM).

NO LOCALITY DATA: 1 (USNM); 4 (OXUM).

MICROPHTHALMOUS MORPH

ERITREA. Guridet, Clermont, 1 (MRAC). ETHIOPIA. Gemu­Gofa: Arba­Minch, 1250m, 21.IX.1974, G. de Rougemont, 1 (MRAC). Gojjam: 5 km E Bahar Dar, 19.X.1973, G. de Rougemont, 3 (MRAC); Tissigat Falls, 19.X.1973, R.O.S. Clarke, 4 (MRAC). Harer: Gode­Ogaden, 7.XI.1974, T.J. Crowe, 2 (MRAC). Shoa: Awash National Park, 1000 m, 14–15.VIII.1971, R.O.S. Clarke, 2 (MRAC); Gibbie Gorge, VII.1971, G. de Rougemont, 1 (MRAC). SOMALIA. Belet Amin (Giuba), P. Basilewsky, 1 (MRAC). Mogadishu, 28.IV.1988, P. Kuchar, 1 (UASM); same, at light, 28–29.IV.1988, P. Kuchar, 1 (UASM). SOMALIA. Blue Nile Province: bank of Rosaires, 12ºN, X.1901, W.L.S. Loat, 1 (OXUM); Kassala Province: Kassala­Haiya, 1–3.XII.1962, Linnavuori, 1 (MRAC).

1 2 species, 9 samples

2 2 species, 3 samples

3 2 species, 5 samples

4 3 species, 10 samples

5 2 species, 7 samples

6 5 species, 17 samples

7 5 species, 9 samples

1 See Table 3 for details about composition of samples.

1 See Table 3 for details about composition of samples. 1 See Table 3 for details about composition of samples.

1 See Table 3 for details about composition of samples. 1 See Table 3 for details about composition of samples.

1 See Table 3 for details about composition of samples.

Figures

FIGURE 9. Dimorphism in Melaenus elegans Dejean. A, Relationship between variation in the ratios 0L/VW and HW/PMW for B, microphthalmous, and C, euphthalmous, specimens.

FIGURE 10. Geographical range of the species of Melaenus Dejean illustrated on an outline map of southwestern Asia, southern Europe, and Africa.