Engertia allolepis, Prokofiev, 2019

Prokofiev, Artem M., 2019, Two new species of Engertia Dalla Torre, 1913 and Philacelota Heller, 1900 from Indonesia and the Philippines with a revised identification key (Coleoptera: Scarabaeidae: Melolonthinae), European Journal of Taxonomy 561, pp. 1-13 : 3-6

Engertia allolepis sp. nov.

urn:lsid:zoobank.org:act:3E17E5EE-4309-4836-9A06-4AB5994E3F32

Figs 1 , 2 A–G

Diagnosis

Engertia , with five lamellae in antennal club of males. Disc of pronotum with irregular callose areas. Elytra with glabrous costae and scale pattern forming longitudinal bands on interstices; scales on elytra lanceolate in 1 st to 3 rd interstices, but intermixed with setiform scales on 4 th and 5 th interstices and along apical margin of elytra. Propygidium with dense long setae; pygidium fully scaled. Abdominal ventrites 2 to 4 with isolated round patches of scales along midline. Aedeagus strongly arcuate, robust.

Etymology

The species epithet is based on the Greek words ‘ allos ’, meaning ‘different’, and ‘ lepis ’, meaning ‘scale’, due to the heterogeneous scales covering the elytra.

Type material

Holotype

INDONESIA • ♂; “Molucc. Ambon / Has / Ex Musaeo van Lansberge”; MNHN.

Description (holotype)

Male

BODY ( Fig. 1 ). Length 18.5 mm, greatest width 7.5 mm. Integument dark reddish-brown; vertex, pronotum and tarsal claws more infuscated; scales and pilosity yellowish to whitish.

HEAD. Clypeus pentagonal, with anterior margin weakly bisinuate in frontal view, slightly produced in middle and conspicuously reflexed; surface rugo-punctate; punctures moderately deep, bearing narrowly lanceolate to spiniform scales becoming much shorter and thinner along midline in posterior half of clypeus. Fronto-clypeal suture conspicuous, weakly concave. Frons rugo-punctate; punctures much denser along inner margins of eyes, bearing lanceolate scales replaced by moderately long erect setae on lateral thirds of anterior half-length of frons; vertex glabrous. Antennae consist of ten antennomeres, with five antennomeres in club ( Fig. 2A ); all antennomeres of club of equal length; 5 th antennomere half as long as 4 th, 3 rd and 4 th antennomeres of equal length; antennomeres of club strongly shagreened, antennomeres of funicle glabrous. Last maxillary palpomere elongate fusiform, with narrow, but deep impression on its outer side. Labrum weakly bilobed, covered by moderately long setae intermixed at sides with narrowly lanceolate scales; mentum deeply concave, bearing long setae along its lateral and posterior margins.

THORAX AND ABDOMEN. Pronotum narrower at base than base of elytra, 1.5 times as broad as long, broadest just before middle, strongly and almost equally convergent anteriad and posteriad; sides straight anteriad, weakly concave posteriad; anterior and posterior angles obtuse; anterior margin bisinuate; posterior margin strongly convex before scutellar shield; all sides of pronotum unbeaded. Pronotum roughly, but not deeply and very unevenly punctured, punctures slightly rugose with interspaces between punctures on disc somewhat callose; glabrous and callose medial longitudinal stripe present; scales on pronotum mostly lanceolate, but intermixed on disc with few setiform scales; moderately long setae present along anterior margin and near anterior angles of pronotum only. Propleura setose, with dense patch of lanceolate scales in their anterior halves. Scutellar shield broadly rounded apically, only punctured along lateral sides; punctures bearing narrowly lanceolate scales. Elytra with five conspicuous glabrous costae; base of elytron somewhat swollen; humeral and apical umbones rather weakly expressed. Interstices shallowly, but densely punctured; punctures of 1 st to 3 rd interstices bearing lanceolate scales, partially replaced by setiform scales in 4 th and 5 th interstices and along apical margin of elytra ( Fig. 2 B–C). Propygidium finely and densely punctured; punctures setigerous, bearing long setae; distal margin of propygidium with few isolated lanceolate scales ( Fig. 2C ). Pygidium densely covered by lanceolate scales ( Fig. 2D ), setose along lateral and apical margins. Prosternum, mesoventrite and metaventrite densely and finely rugo-punctate, densely covered with long setae; disc of metaventrite, metepimeron and metepisternum bearing some scales. First abdominal ventrite flat in middle; 1 st and 2 nd ventrites setose, remaining ventrites with isolated setae in their lateral thirds only, except last visible ventrite bearing rather dense setae of moderate length along its distal margin; all abdominal ventrites covered by ovate (lanceolate in uppermost parts) scales, more densely aggregated in uppermost reaches of each ventrite, forming small round patches of scales on 2 nd to 4 th ventrites along midline of abdomen ( Fig. 2E ); sutures between 2 nd and 5 th abdominal ventrites obliterated in middle.

LEGS. Protibiae unidentate, with spur short and thick; middle and hind tibiae gracile; apex of hind tibiae with 12 separated bristles. Femora setose; lanceolate scales present on hind femora only; tibiae with sparse narrow scales and spiniform setae; tarsi with setae only. Tarsomeres 1 – 4 shortened, especially of fore tarsi; 1 st tarsomere of hind tarsi equal to 2 nd in length. Claws bifurcate, with lower lobe situated slightly closer to base of claw, parallel to upper one, distinctly shorter, but as broad as the latter.

GENITALIA. Aedeagus ( Fig. 2E, G ) strongly arcuate, robust; phallobase remarkably deepened distally; parameres considerably narrowed toward apex, their ventral contour very weakly arcuate and dorsal contour almost straight; apical extensions of parameres small, oval, not upturned.

Female

Unknown.

Differential diagnosis

Engertia allolepis sp. nov. is unique within the genus in the possession of both lanceolate and setiform scales in the outer elytral interstices (vs elytral scales more or less homogeneous in shape in all interstices in the other Engertia spp.; see Fig. 2H for representation). In other respects this new species is most similar to E. papuana ( Moser, 1913) , but differs from the latter in the much longer and denser pilosity of the propygidium (compare Fig. 2C and 2I ) and in the somewhat callose disc of the pronotum. The aedeagi of E. allolepis sp. nov., E. amboinae ( Brenske, 1897) , E. germanica Prokofiev, 2016 , E. papuana and E. setifera ( Moser, 1913) are very similar to each other, but the aedeagus of E. allolepis sp. nov. is more arched in lateral view than that of the aforementioned species except E. germanica , and it can be further distinguished from the aedeagi of all the other species mentioned above in the deeper and broader apical portion of the phallobase and in the more robust and massive parameres (compare Fig. 2G with 2J as an example).

Engertia allolepis sp. nov. is known from Ambon Island, where two other members of the genus are distributed: E. amboinae and E. setifera . Besides the heterogeneous vestiture of the elytra and the more robust aedeagus, the new species can be distinguished from E. amboinae by the scales in the elytral interstices being much narrower (lanceolate to setiform vs ovoid: Fig. 2K ), scales along midline of the abdominal ventrites aggregated into spots (vs not aggregated), propygidium with long (vs short) setae, and from E. setifera by the pygidium being densely covered with scales (vs mainly setose: Fig. 2L ), scales along midline of the abdominal ventrites aggregated into spots (vs not aggregated), and scales present on labrum and metaventrite (vs absent).

Figures

Fig. 1. Engertia allolepis sp. nov., habitus, holotype, ♂ (MNHN). Scale bar = 2.5 mm.

Fig. 2. A–G. Engertia allolepis sp. nov., holotype, ♂ (MNHN). A. Antenna. B. Lateral part of the elytron. C. Apical margin of elytra and propygidium. D. Pygidium. E. Abdominal ventrites 2–4. F. Parameres, dorsal view. G. Aedeagus, lateral view. — H–J. E. papuana (Moser, 1913), ♂, from Sentani (cAP). H. Lateral part of elytron. I. Apical margin of elytra and propygidium. J. Aedeagus, lateral view. — K. E. amboinae (Brenske, 1897), ♂, from Ambon (MNHN), lateral part of elytron. — L. E. setifera (Moser, 1913), ♂, from Seram, pygidium (cAP). Scale bars are in common for B, H and K, and for F–G and J. Scale bars: A–B, H, K = 1.5 mm, C–G, I–J, L = 2.5 mm.