Bolboceras inaequale Westwood, 1848

Krikken, Jan, 2013, Distinguishing Bolboceras inaequale Westwood, 1848 and two new relatives from India (Coleoptera, Geotrupidae, Bolboceratinae), ZooKeys 276, pp. 55-66 : 58-61

Bolboceras inaequale Westwood, 1848 Figures 1 –49– 10, 1316-19

Bolboceras inaequalis Westwood, 1848: 386 (description); 1952: 24 (description), pl. IV: figs 14, 14a.

Bolboceras inaequale : Paulian 1941: 11, 33 (records from Sudan, Senegal).

Indobolbus inaequalis : Krikken 1984: 34 (recombination in checklist).

Bolboceras inaequale : Krikken 2011: 239, 240 (transfer to original combination).

Material examined.

Syntype, unsexed, from "Centr Ind \ [J.B.] Hearsey" (handwritten), and two more specimens from Westwood’s collection(OUMNH, see comments below).

Non-type material (specimens without data excluded). Bangladesh: Dhaka: Dacca [Dhaka], ex Pascoe coll., 1 spm., in BMNH. Dinajpur: Dhanjuri, v/1963, Mapelli, 2 spm., in MHNG. vi/1963, Mapelli, 2 spm., in MHNG. Rajshahi: Andharkota, vii/1963, Mapelli, 1 spm., in MHNG.

India: Bihar: Buxar, ex Felsche coll., 1 spm., in SMTD. Chapra, Mackenzie, 6 spm., in BMNH. Pusa, 03/viii/1926, Pillai, at light, 1 spm., in BMNH. Pusa, 1913, Fletcher TB, 1 spm., in BPBM. 19/vi/1911, TMH, 1 spm., in BMNH. 30/vii/1915, Bahadur U, at light, 1 spm., in BMNH. 28/vii/1928, Sarkar SC, 1 spm., in BMNH. 20/vii/1908, TNS, at light, 1 spm., in BMNH. 24/vii/1919, Austin GD, verandah 1-10 PM, 1 spm., in BMNH. 08/vii/1915, at light, 1 spm., in BMNH. 12/vii/1915, at light, 1 spm., in BMNH. 05/vii/1924, Mukerjee, 1 spm., in BMNH. 31/vii/1918, Ghosh, underground, 1 spm., in BMNH. 15/viii/1908, RDD, at light, 1 spm., in BMNH. 20/viii/1919, Austin GD, 1 spm., in BMNH. 08/ix/1912, NML, 1 spm., in BMNH. 27/ix/1915, Bahadur U, at light, 1 spm., in BMNH. 04/ix/1915, Bahadur U, at light, 1 spm., in BMNH. 04/x/1915, Bahadur U, at light, 1 spm., in BMNH. 18/xi/1920, Sarkar SC, 1 spm., in BMNH. Tamil Nadu: Madras [Chennai; to be confirmed], ex Felsche coll., 2 spm., in SMTD. Uttar Pradesh: Allahabad, ex Bowring coll., 1 spm., in BMNH. Sitapur, HGC [Champion HG], 4 spm., in BMNH. West Bengal: Calcutta [Kolkata], 1 spm., in BMNH. Kalkutta [Kolkata], ex Felsche coll., 5 spm., in SMTD.

Bengal: unspecified, Parish HM, 1 spm., in BMNH. unspecified, ex Gillet coll., 1 spm., in IRSNB.

India: “Inde”, unspecified, ex Boucomont coll., 1 spm., in MNHN. unspecified, 1 spm., in USNM.

Total 47 males and females, 33 collection records, and Westwood’s material.

Diagnosis.

Ridge (or saddle) separating discomedian and discolateral concavities on pronotum narrow, lowered in relation to surrounding discal surface; discoparamedian tubercles approximated (connected by saddle), their tip subacute; discolateral concavity in major males extending down, onto anterolateral surface. Posterior edge of discomedian concavity usually distinctly W-shaped in major individuals, in minors the pronotal ornamentation may be only just distinct (in oblique view); bottom of concavities more or less sericeous. Interocular ridge low, not reaching paraocular ridge on either side, situated between posterior part of eyes. Anterolateral corners of clypeus usually protuberant (in majors intervening ridge concave in axial view). Scutellum usually closely punctate. Intermesocoxal lobe of metasternum anteriorly with arcuate ridge. Aedeagus (Fig. 13) with acuminate parameres, median apparatus with pair of strongly sclerotized lateral stalks, their tip broad, shortly recurved-hooked. Colour uniformly brown. Body length usually 11-13, some series down to ca 9 mm or less (see next section).

Variation.

There are small individuals (minors) from Northeast India and Bangladesh (a male from Dhanjuri in Bangladesh pictured here, ca 9 mm long, Figs 3-4, 10, 18-19), characterized by a minimal set of pronotal protrusions and impressions, but still with distinct traces of the basic pattern - and also with a smaller, but externally quite similar aedeagus. Some intermediates between these minors and the real majors (including the type) were seen. At this moment I find no morphological support for ranking the minors as a separate taxon - informative material from different locations required. Paulian (1941) mentions a length range for Bolboceras inaequale of 7-12 mm.

Sexual dimorphism.

Apparently no notable sexual dimorphism.

Comments.

Note the recent retransfer of this species from Indobolbus Nikolajev, 1979, to Bolboceras Kirby, 1819, and the ensuing suffix change of the species-group name, following the ICZN (2006) ruling. The specimen of Bolboceras inaequale labelled as the type (OUMNH) cannot be considered the holotype, as there are two more historical specimens having the usual large (pale blue) rhomboid label with " W" (meaning Westwood’s original collection), one of them with this label only. The specimen here qualified as syntype has a curatorial label of the 1960s, indicating its registration as Coleoptera type 516, plus additional post-Westwood labels. The three specimens are considered conspecific, and consequently, at this moment, an explicit lectotype designation appears unnecessary.

Distribution.

India (southern occurrences to be confirmed), Bangladesh; northern sub-Saharan Africa (needs confirmation).