Odonteus gandhara Carpaneto & Mignani

Carpaneto, Giuseppe M. & Mignani, Roberto, 2005, A new species of the genus Odonteus (Coleoptera: Geotrupidae) from northern Pakistan, Zootaxa 968, pp. 1-10 : 2-8

Odonteus gandhara Carpaneto & Mignani , n. sp.

( Figs. 1–6 )

Type material. Holotype: male, Pakistan, NW Frontier Province, Kagan (= Kaghan) Valley, 8 km W of Malkandi, 2140 m asl, 6 August 1998, T. Csovari & L. Mikus leg. Paratype: female, from the type locality. Both have been deposited in the Zoological Museum of Roma Tre University, Rome (G. M. Carpaneto collection).

Diagnosis. The new species is easily distinguished from the other widespread species occurring in the Old World, O. armiger , by the following characters ( Figs. 1–4 , Table 1): (1) head horn of male immovable, with an enlarged basis ( Figs. 1 a–1b); (2) eye almost entirely divided by canthus ( Fig. 1 b); (3) sensory area on the external side of the last antennomere not exceeding 3/5 of the exposed area in length ( Figs. 1 a, 2a, 3, 4), as in O. orientalis ; (4) clypeus and pronotal sides with punctures large and deep but not rugose ( Figs. 1, 3 ); (5) pronotum of male with a single low elevation in the middle without a pair of toothlike tubercles in front and two high, rounded (not horn­like) lateral ridges extending up to posterior margin ( Figs. 1 a–1b); (6) pronotal sides with an obtuse angle in the middle and subparallel in their posterior half ( Figs. 1 a, 3); (7) posterior angles of pronotum not protruding outwards ( Figs.1 a, 3); (8) medial areas of pronotum near to base impunctate ( Figs. 1 a, 3); (9) metasternal plate wide and slightly concave, glabrous in the middle; (10) the shape of male genitalia ( Fig. 5–6 ).

The female of O. gandhara has the vertex with a transverse ridge and slight, smooth lateral elevations ( Fig. 3 ) while the female of O. armiger has the transverse ridge with two distinct and well­separated tubercles. In the unique known specimen (holotype, female) of O. orientalis the vertex structure is similar but has more marked lateral elevations. Moreover, the lateral margins of the pronotum in the female of O. orientalis are sinuate in the posterior half, with posterior angles protruding outwards. In the female O. gandhara , the lateral margins of the pronotum are subparallel in the posterior half, without protruding angles. In O. orientalis , the transverse carina of the pronotum is trisinuate and the pronotum is strongly and closely punctate anteriorly. Furthermore, O. gandhara has the pronotum transverse carina evenly arcuate, while O. orientalis has a small indentation in the middle of the carina.

Character Odonteus gandhara Odonteus armiger

Colour Ventral side of the body black brown

Head eye not entirely divided by can­ entirely divided by canthus

thus

clypeal punctures large and deep rugose

sensory area on last not exceeding 3/5 of the exceeding 4/5 of the antennomere exposed area in lenght exposed area in lenght

male horn immovable movable

male horn base enlarged not enlarged

female ridge of vertex with very slight elevations with two distinct and well at sides separated tubercles

punctures of lateral sides large and deep rugose

base medial areas impunctate punctuate

male middle elevation single, low, without ante­ double, formed by a pair of rior pair of tooth­like tuber­ tooth­like tubercles cles

Pronotum male lateral ridges high but rounded, horn­like, not reaching pos­

not horn­like, reaching terior margin posterior margin

female ridge feebly arcuate forward distinctly arcuate forward

lateral sides with an obtuse angle in the roundly converging from middle, subparallel base to apex, slightly sinuin posterior half ate in posterior half

posterior angles not protruding outwards protruding outwards

Metasternum surface of median plate wide and slightly concave, narrow, flat, almost com­

hairless in the middle pletely hairy

Male genitalia parameres distinctly curved ventrally not distinctly curved ven­

trally

median lobe as long as parameres shorter than parameres Description of the holotype. Male, length 10 mm, greatest width 6.2 mm. Entirely black (including ventral parts), moderately glossy. Antennal club reddish brown. Legs black, tarsi dark brown. Setae yellowish brown, particularly long and dense beneath.

Clypeus (length 1.2 mm) widely semicircular, entirely marginated. Clypeal surface with punctures large and deep but not rugose. Medial longitudinal ridge distinct and reaching anterior margin of clypeus but terminating before straight clypeo­frontal suture. Genae rounded, eye not entirely divided by canthus. Frontal horn immovable, long and moderately curved, enlarged at base. Clypeo­genal (fronto­lateral) ridges slightly curved backwards, reaching almost half of eye. Labrum partially covered by clypeus, anteriorly emarginated but irregular. Sensory area on the external side of the last antennomere not exceeding 3/5 of the exposed area in length ( Figs. 1 a, 2a, 3, 4).

Pronotum distinctly marginate at anterior and posterior edge, finely at sides; maximum length in the middle (length 3.5 mm), maximum width at posterior half (6.2 mm). Anterior angles largely obtuse, posterior angles almost right and not protruding outwards. Pronotal sides with an obtuse angle in the middle, subparallel in posterior half, and converging in anterior half. Pronotal base sinuate at sides in front of humeral umbone. Anterior half of pronotum with a straight carina in the middle reaching the medial elevation, then diverging to delimitate a central groove towards pronotal base. Lateral ridges prominent and rounded, delimitating two deep and large depressions. Pronotal surface with punctures large and deep but not rugose; irregularly distributed; medial elevations near to pronotal base impunctate except for central groove.

Scutellum large and broad, with sides parallel at base, then converging toward rounded apex, finely and sparsely punctate. Elytra with distinctly impressed striae formed by large, rounded and well separated punctures. Intervals slightly convex with minute punctures. Second and fifth stria vanishing from apical third of elytra; eleventh stria starting well after humeral umbone.

Metasternal plate wide and slightly concave, glabrous medially.

Protibia with 8 teeth along outer margin (including the smallest one located near base); tooth size increases towards apex.

Mesocoxae contiguous, not separated by sternal plate projections; metacoxae subcontiguous.

Median lobe of aedeagus as long as parameres ( Fig. 5 a), evenly curved, with apex enlarged and directed downward. Lateral profile of aedeagus strongly convex, with parameres curved downward ( Fig. 5 b).

Paratype variability. The female paratype shares all the major morphological characters with the holotype, and shows the usual sexual differences of the genus as expressed in the following features:

– clypeo­frontal suture fine but distinct, vertex crossed by a short transverse ridge with slight and smooth lateral elevations;

– pronotum with a transverse ridge; evenly arcuate at about apical third with a small tubercle at each end, narrowly separated and slightly anterior to carina.

The clypeo­genal ridges are more developed in the female, extending up to the posterior margin of the eye. Both male and female have two impunctate medial areas near to the pronotal base (in contrast to O. armiger ). Although the female morphology is difficult to use in diagnosing species of this genus, some of the above mentioned character states (transverse ridge of vertex and pronotum, posterior angles of pronotum) could be used in separating the new species from O. armiger and O. orientalis . As indicated in diagnosis, the female of the new species has the vertex intersected by a transverse ridge with two adjacent elevations ( Fig. 3 ) while the female of O. armiger has the transverse ridge of the vertex with two distinct and well­separated tubercles. The frontal and pronotal structure also distinguishes the new species from O. orientalis . In fact, O. gandhara has less developed tubercles on the vertex, the pronotal transverse carina evenly arcuate, and pronotal subparallel lateral margins without protruding angles.

Etymology. The new species is named after the ancient Buddhist Gandhara Civilization (500 BC to 10 AD), which is celebrated by many archaeological sites in the North West Frontier Province.

Taxonomy and redefinition of the genus. The genus Odonteus (as well as Bolbocerosoma Schaeffer, 1906 and Bolbocerodema Nikolajev, 1973 ) is often diagnosed by the eye entirely divided by the canthus. This character status was not reported by Samouelle (1819), Kirby (1819) or Wallis (1928) in their descriptions, but was highlighted in identification keys to local faunas (e.g., Howden 1955, Woodruff 1973, Baraud 1992, Jameson 2002, Nikolajev 2003). In fact, the eye is distinctly divided in most specimens of O. armiger , but an interrupted canthus can be observed in some specimens. We examined a male from Slovenia (Capodistria, R. Pittino Collection) which has the eye not entirely divided by canthus, and several specimens which have the posterior tract of the canthus thinner. Also some North American species (e.g., O. darlingtoni Wallis, 1928 ), have the canthus thinner posteriorly. The two Asiatic species, O. gandhara and O. orientalis , have the canthus clearly interrupted and not entirely dividing the eye. Therefore, the character state of the canthus entirely dividing the eye should not be used as a diagnostic for this genus.

A worldwide revision of all the Odonteus species is required to give a redefinition of the genus within the family. Despite of the fact that O. gandhara and O. orientalis show only a partial division of the eye by the canthus, they unequivocally belong to the same genus as O. armiger and its Nearctic relatives. Our opinion is based on the following shared characters:

1) External side of the last antennomere with a well­defined, more or less developed sensory area;

2) Strong sexual dimorphism: male with an elongate, narrow horn curved back over the pronotum, and a typical pronotal ornamentation (deep excavations on each side of a median protuberance, laterally bordered by acute carinae);

3) Mesocoxae contiguous, not separated by sternal plate projections;

4) Seven elytral striae between suture and humeral umbone;

5) The particular morphology of male genitalia, characterized by a long and sclerified median lobe, curved toward dorsum, as described by Wallis (1928) and Zunino (1984).

The first character, dealing with the last antennomere, has never been quoted in the literature and is a unique feature of this genus: a similar sensory area does not occur in any genus of the family Geotrupidae . This character emphasizes the isolated position of the genus Odonteus , as suggested by Zunino (1984) on the basis of the male genitalia. According to a recent research based on larval morphology ( Verdú et al. 2004), the Odonteus lineage appeared to constitute the closest sister group to the subfamily Geotrupinae , and was therefore removed from Bolboceratinae .

Based on a combination of three major morphological characters, i.e. the black colour, horn immovability and the shape of the median lobe of the aedeagus, we consider that the new species is related to O. obesus LeConte, 1859 and O. falli Wallis, 1928 , both of which are endemic to the Nearctic Region. On the contrary, the other Palaearctic species, O. armiger , is probably related to O. filicornis ( Say, 1823) and its Nearctic allies.

Zoogeography and ecology. The type locality of O. gandhara is located within the Himalayan transitional zone, between the Palaearctic and the Indo­Malayan (= Oriental) zoogeographical regions. This is a broad area where taxonomic groups of both the regions occur together (see: Corbet & Hill 1992). Mittal (1998) defined O. orientalis as a representative of the “Oriental Region”. We do not agree with this attribution because the Himachal Pradesh is also located at the border between the Palaearctic and Indo­Malayan region, in the Himalayan transitional zone.

An ecological description of the Kaghan Valley (where O. gandhara was found) was provided by Schickhoff (1995). The vegetation features of the type locality fit well to those expected for a landscape of mountains in the Himalayan transition zone (Zafeer Saqib, pers. com.). Kaghan Valley lies in the northernmost portion of Mansehra District and is surrounded by mountains that rise to over 5,000 m. The climate is characterized by long frozen winters and short cold summers, with an annual rainfall of 1,545 mm, mostly recorded from June to September. Himalayan coniferous forests of Pinus wallichiana , Abies pindrow , Cedrus deodara and Picea smithiana , followed by Juniperus woodland on sunny slopes, dominate the natural vegetation. The type locality, at 2,140 m, is near to the transitional belt where gymnosperms are mixed with deciduous trees of the genera Acer, Prunus, Juglans , Aesculus , and Quercus .

The distribution pattern of the genus Odonteus is similar to that of the genus Thalycra Erichson ( Coleoptera : Nitidulidae ), with 15 or 16 species in North America, one widespread European species, and one species in northern Pakistan (Howden 1961, Audisio (pers. com.)). Quite intriguingly, it seems that Thalycra species feed on subterranean fungi, like Odonteus species were reported to do ( Howden 1955).

Figures

FIGURES 1 – 4. Odonteus gandhara n. sp.: head and pronotum of male in dorsal (1 a) and lateral view (1 b); head and pronotum of female (4). O. armiger (Scopoli) (Southern Moravia: Hustopece): head and pronotum of male in dorsal (2 a) and lateral view (2 b); head and pronotum of female (3).

FIGURES 5 – 6. Aedeagus of Odonteus gandhara n. sp. (5) and O. armiger (Scopoli) (Southern Moravia: Hustopece) (6): dorsal view (a) and lateral view (b).