Mesolycus Gorham, 1883

Kazantsev, Sergey V., 2004, Contribution to the knowledge of Macrolycini with description of Calcaeron, new genus (Coleoptera, Lycidae), Zootaxa 493, pp. 1-32 : 10-12

Mesolycus Gorham, 1883 , nom. rev.

Flabellodilophotes Pic, 1912: 9 , syn. n.

type species: Dilophotes (Flabellodilophotes) obscurus Pic, 1912: 9 (by original monotypy). Dilophotellus Kleine, 1925: 134.

type species: Dilophotellus tricostatus Kleine, 1925: 135 (by original designation). Biphilodes Kazantsev, 2000: 329, syn. n.

type species: Dilophotes (Biphilodes) ilyai Kazantsev, 2000: 329 (by original designation).

Redescription

Head transverse, slightly narrowed behind eyes. Frons plane at blunt angle with vertex. Gular area narrow, not separated by sutures ( Fig. 18 ). Sub­antennal suture rudimentary, coronal suture incomplete ( Fig. 20 ). Tentorium represented by a pair of posterior arms ( Fig. 21 ). Labrum transverse, feebly emarginated medially, not rigidly attached to epistomal sulcus ( Fig. 20 ). Eyes spherical. Mandibles evenly rounded ( Figs. 18, 20 ). Maxillary palpi 4­segmented, with ultimate palpomere more or less parallel­sided and flattened at apex ( Fig. 18 ). Mentum rudimentary, submentum present. Prementum undivided. Labial palpi 3­segmented, slender, ultimate palpomere more or less parallel­sided and flattened at apex ( Fig. 19 ). Antennal prominence inconspicuous, antennal sockets more or less approximate ( Fig. 20 ). Antennae 11­segmented, compressed from antennomere 3. Antennomere 2 small, transverse and more than 5 times shorter than antennomere 3. Antennal pubescence short and decumbent, sometimes with scaliform setae on antennomeres 3 to 11. Pronotum square or elongate, conspicuously produced anteriorly, with conspicuous hind angles; median suture manifest only in anterior half ( Fig. 22 ). Prosternum narrow, Yshaped, divided into median sclerite and lateral sulci ( Fig. 22 ). Mesothoracic spiracles well sclerotized, hooded, not extending laterally beyond coxal line ( Fig. 22 ). Mesoscutum composed of three basic sclerites, separated by prominent sutures, with scutellum relatively wide and feebly emarginate at apex ( Fig. 23 ). Mesepimeron narrow ( Fig. 24 ). Elytra slightly narrowing posteriorly, usually dehiscent behind middle, with three primary costae, costae 2 and 3 gradually weakening towards apex, costa 1 robust only basally, interstices with irregular reticulation; traces of a missing (primary) costa sometimes noticeable in close proximity of humerus; elytral pubescence uniform. Metathoracic spiracles well developed. Metathoracic wing with wedge cell absent ( Fig. 25 ). Metasternal suture almost complete ( Fig. 22 ); metendosternite simple, without arms ( Fig. 26 ). Procoxae elongate, approximate distally; mesocoxae transverse, separated; metacoxae divided by sutures into presumably coxal, meral and trochantinal parts, with basal part similar to mesocoxa ( Figs. 22 , 27 ). Trochanters elongate, about 2 times longer than wide, but considerably shorter than femurs, connected to femurs apically; tibiae subequal in length to pertinent femurs, tibial spurs absent; tarsi narrow, tarsomeres 3 and 4 widened, plantar pads present on tarsomeres 1 to 4; all male claws bifid apically; female claws with acute tooth near base or in the middle. Abdominal spiracles located dorsally, relatively distant from the edge of sternites ( Fig. 28 ); tergites without median longitudinal line. Ultimate female sternite without spiculum gastrale ( Fig. 28 ). Male ultimate sternite with long, basally asymmetrical spiculum gastrale. Female genitalia with elongate styli, relatively short coxites and relatively short free valvifers ( Fig. 29 ). Aedeagus with symmetrical median lobe and internal sac structures and asymmetrical phallobase; inner sac structures often developed into movable upper and lower plates; median lobe provided apically with hood, often separated by suture ( Figs. 30–47 ).

Remarks

Mesolycus is characterized by the following combination of characters: relatively short antennae hardly reaching over the elytral middle in both sexes, blunt angle between the vertex and frons planes, relatively long pronotum with anterior median suture, hooded mesothoracic spiracles, metathoracic wing with the absent wedge cell, usually present plantar pads on tarsomeres 1 and 2 (absent in M. shelfordi ), absence of a median longitudinal line on tergites, free valvifers and symmetrical median piece, including the inner sac structures, of the aedeagus. The upper plate of the inner sac structures, the one adjacent to the hood of the median lobe ( Figs. 42–46 ) is referred to by Bic (2002) as lower plate, though it reaches a position when it may be lower to the other plate only at one extreme of its up­and­down movement amplitude ( Fig. 46 ).

The type specimen of the type species of Flabellodilophotes , F. obscurus Pic , has not been found at the Museum National d’Histoire Naturelle in Paris, where the Pic collection is located; nevertheless, its description indicates to characters (i.e. the large eyes that are wider than the pronotum, the latter being long and strongly produced anteriorly, the broad third male antennomere with the fourth and following ones flabellate) that rather confidently bring the species in question to Mesolycus . A male specimen from Western Sabah, Malaysia, a locality close to the type one ( Brunei), agreeing with the above description, has also been found to belong to Mesolycus . The flabellate antennae of M. obscurus (Pic) , comb. nov. (though reaching the elytral apices, as in Dilophotes ) are a widespread homoplasy in the Lycidae , and, as not supported by other possible apomorphies, do not allow regarding the taxon as a valid genus/subgenus. Therefore, I am inclined to consider Flabellodilophotes a junior synonym of Mesolycus .

Biphilodes introduced as a subgenus of Dilophotes on the basis of reduction of elytral costa 1, now, with more material available, was found to be synonymous with Mesolycus . The aforesaid reduction, though more or less manifest in all allied species, appeared to lie within limits of infraspecific variability. Certain peculiarities of the aedeagi of the ilyai species group evidently do not justify separation of the clade at the subgenus level.

Figures

FIGURES 18 – 24. Details of Mesolycus shelfordi (Bourgeois). 18 — head, ventrally; 19 — labium; 20 — head, dorsally; 21 — head, laterally; 22 — thorax, ventrally; 23 — mesoscutum, internally; 24 — mesepimeron and mesepisternum, internally. CS — coronal suture; MR — meron; PM — prementum; SaS — sub­antennal suture; TN — trochantin.

FIGURES 25 – 31. Details of Mesolycus shelfordi (Bourgeois). 25 — metathoracic wing; 26 — metendosternite; 27 — metacoxa, internally; 28 — female ultimate sternite; 29 — female genitalia; 30 — aedeagus, ventrally; 31 — same, laterally. MR — meron; TN — trochantin.

FIGURES 40 – 47. Aedeagi of Mesolycus. 40 — M. mediozonatus Nakane, ventrally; 41 — same, laterally; 42 — M. hubeicus sp. nov., laterally; 43 — same, inner sac structures, apically; 44 — M. nanensis sp. nov., laterally; 45 — same, inner sac structures, apically; 46 — M. murzini sp. nov., laterally; 47 — same, inner sac structures, apically. UP — upper plate.