Megistopalpus Guillebeau, 1895

Gimmel, Matthew L., 2013, <strong> Genus-level revision of the family Phalacridae (Coleoptera: Cucujoidea) </ strong>, Zootaxa 3605 (1), pp. 1-147 : 47-48

9. Megistopalpus Guillebeau, 1895

( Figs. 2f ; 39a, b )

Megapalpus Guillebeau 1893 b: 297 . Type species: Megapalpus simoni Guillebeau 1893 , fixed by monotypy.

Megistopalpus Guillebeau 1895 : xxvii. [replacement name for Megapalpus Guillebeau, 1893 ]

Type material. Megapalpus simoni Guillebeau : one syntype found, here designated as lectotype, point mounted, “ Aden [handwritten] // Megapalpus \ Simoni \ Guilb. [handwritten] // LECTOTYPE \ Megapalpus \ simoni Guillebeau \ des. M.L. Gimmel 2009 [red label]” ( MNHN). Two specimens were mentioned in the original description. The lectotype is designated in order to stabilize the generic and specific names.

Diagnosis. The only phalacrid whose maxillary palps approximate the length of the antennae. Otherwise quite similar to Pseudolibrus , with a protibial ctenidium, large scutellar shield, and nine nearly complete, distinct elytral striae, though members of the latter genus are smaller (2.7 mm or less).

Description. Large, total length 3.2 mm. Color solid testaceous ( Fig. 39a ). Tibial spur formula 2-2-2, tarsal formula 5-5- 5 in female, male unknown.

Head. Not constricted behind eyes. Eyes medium-sized; facets convex; weakly emarginate medially; without posterior emargination; periocular groove absent. Frontoclypeus not emarginate above antennal insertion; clypeal apex arcuate-truncate. Antennal club loosely 3-segmented, club weakly asymmetrical; antennomere XI weakly turbinate. Maxillary palp ( Fig. 2f ; Fig. 39b ) extremely long, approaching length of antenna, palpomeres II–IV flattened, clavate, palpomere II longest. Labial palp unmodified, labial palpomere III elongate, fusiform.

Thorax. Pronotum with scattered microsetae; without scutellar lobe. Procoxal cavity with anterolateral notchlike extension; prosternal process weakly angulate in lateral view, somewhat setose preapically, without spinelike setae at apex. Protibia with ctenidium on kickface extending about one-third length of tibia. Scutellar shield large, about as long as greatest length of eye. Elytron without spectral iridescence; with nine distinct, moreor-less complete impunctate striae (including sutural), medialmost stria somewhat convergent apically, second stria (first discal) fusing with sutural stria before apex; with distinct transverse strigae, strongest laterally; lateral margin with row of tiny, sawtooth-like setae. Mesoventral plate notched anteriorly, not extending posteriorly to metaventrite, forming procoxal rests; mesoventral disc depressed medially, setose; mesanepisternum with complete transverse carina; mesocoxae approximate, separated by less than half width of a coxal cavity. Mesotarsomere III not bilobed. Metaventral process extending anteriorly just to halfway point of mesocoxae; metaventral postcoxal lines not separated from mesocoxal cavity margin; discrimen long, extending more than halfway to anterior margin of metaventral process. Anterior margin of metacoxa with emargination sublaterally; metacoxal plate with transverse line; metatibial foreface with apical ctenidium straight, perpendicular overall to long axis of tibia; spurs cylindrical, longest spur greater than width of tibial apex; metatarsomere I longer than metatarsomere II, but shorter than remainder of tarsus, joint between I and II rigid.

Abdomen. Abdominal ventrite I without paired lines.

Immature stages. Unknown.

Bionomics. Unknown.

Distribution and diversity. Known only from the lectotype collected in Yemen (“ Aden ”) and from a Somali specimen (MSNG). The two may not be conspecific.

Included species (1):

Megistopalpus simoni (Guillebeau, 1893) (Distribution: Yemen) (type!)

Discussion. Since the genus is known only from two specimens, one a primary type, I did not disarticulate a member of this morphologically interesting genus for examination under a compound scope. Accordingly, the description above is relatively scanty and the genus was excluded from the phylogenetic analysis. However, based on external morphology it is quite similar to the genus Pseudolibrus , therefore I have included it in the Pseudolibrus -group.

Figures

FIGURE 2. Key characters for Phalacridae. (a) Schematic of dorsal characters showing small scutellar shield and two sutural striae. (b) Schematic of dorsal characters showing large scutellar shield and one sutural stria. Frontal view of head capsule of (c) Stilbus; (d) Phalacrus; (e) Tolyphus. (f) Maxillary palpus of Megistopalpus. Labial palpus of (g) Grouvelleus; (h) Phalacrinus (scale bar = 0.5 mm); (i) Phaenocephalus (scale bar = 0.2 mm). Dorsal view of head capsule of (j) Phaenocephalus; (k) Phalacrinus; (l) Acylomus (scale bars = 0.5 mm). Ventral view of head capsule of (m) Xanthocomus; (n) Nesiotus.

FIGURE 39. Photographs. Megistopalpus simoni, lectotype: (a) dorsal; (b) view of antenna and maxillary palp. Phalacropsis dispar: (c) dorsal. Phalacrus rufoguttatus: (d) dorsal; (e) ventral. Austroporus sp.: (f) dorsal. Platyphalacrus lawrencei: (g) dorsal; (h) lateral; (f) ventral.