Philacelota leucothea, 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 : 6-12

Philacelota leucothea sp. nov.

urn:lsid:zoobank.org:act:BF182F51-5D7C-4F3E-937D-ED8458AADF21

Figs 3–4 , 5 A–B

Diagnosis

Philacelota with squamose vestiture. Disc of pronotum with narrow, longitudinal callose stripe. Elytra evenly scaled in males, while in females the scaled areas are intermixed with glabrous ones to form a variegated pattern. Propygidium of males with short acicular setae and sparse long setae, of females with short setae only; pygidium fully scaled in males, but with glabrous medial longitudinal stripe in females. Scales along midline of abdominal ventrites 2 to 4 evenly distributed. Aedeagus of characteristic shape.

Etymology

The name of this new species reflects the white scale covering of the beetles. Leucothea (‘white goddess’) is a poetic epithet of a Greek goddess. The species epithet is treated as a noun in apposition.

Type material

Holotype

PHILIPPINES • ♂; “N O Luzon / Philippines Ch. Semper ”; MNHN.

Paratypes

PHILIPPINES • 1 ♂, 2 ♀♀; same collection data as for holotype; MNHN .

Description (holotype)

Male

BODY ( Fig. 3A ). Length 15.0 mm, greatest width 6.5 mm. Integument reddish-brown; scales and pilosity whitish.

HEAD. Clypeus nearly crescent-shaped, with anterior margin arcuate in frontal view and weakly reflexed; surface roughly rugo-punctate, with long spiniform (slightly broadened at base, pointed at tip) scales. Fronto-clypeal suture conspicuous, almost straight. Frons and vertex roughly rugo-punctate; punctures denser on anterior half of frons; posterior half of frons and vertex with a narrow longitudinal callosity along midlength. Frons and vertex covered by elongate spiniform scales, denser toward inner margins of eyes, intermixed with sparse, moderately long setae. Antennae consist of 10 antennomeres, with seven antennomeres in club ( Fig. 4A ); all antennomeres of club of equal length; 3 rd antennomere with a strong anteromedial process; antennomeres of club strongly shagreened, antennomeres of funicle glabrous. Last maxillary palpomere elongately fusiform, with outer side impressed. Labrum weakly bilobed, covered by spiniform scales and sparse long setae; 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 in middle, distinctly more convergent anteriad than posteriad; sides straight anteriad, but very weakly concave posteriad; anterior and posterior angles obtuse; anterior margin strongly concave, slightly bisinuate in middle; posterior margin strongly convex before scutellar shield; all sides of pronotum unbeaded. Pronotum not roughly rugo-punctate, with a narrow longitudinal medial callosity along its anterior half, covered by acicular to narrowly lanceolate scales being much smaller in size on sides than on disc, with setae along its anterior and lateral margins only. Propleura setose, with few small acicular scales along lateral margins only. Scutellar shield broadly rounded apically, not roughly rugo-punctate, covered with narrowly lanceolate scales becoming acicular and much denser along lateral margins. Elytra with three indistinct costae bearing scales; base of elytron with a swollen margin; humeral and apical umbones somewhat callose, glabrous; surface of elytra somewhat impressed behind humeral umbones. Interstices shallowly, unevenly and irregularly punctured; punctures somewhat rugose; scales small, rather evenly covering entire surface of elytra, lanceolate to narrowly lanceolate, becoming acicular close to margins. Propygidium ( Fig. 4B ) finely and densely punctured; its basal half covered with small acicular setae intermixed with sparse long setae along basal margin; setae replaced on distal half by small ovoid scales. Pygidium ( Fig. 4C ) fully covered by small ovoid scales, setose at apical margin only. Prosternum, mesoventrite and metaventrite densely and finely rugo-punctate, densely covered with long adpressed setae; metepimeron and metepisternum possessing scales; metaventrite lacking scales. First abdominal ventrite carinate in middle, covered with short, adpressed, hair-like setae replaced by densely setting, scale-like setae along posterior margin; 2 nd abdominal ventrite covered by small lanceolate scales intermixed with adpressed setae on its anterior half; remaining abdominal ventrites covered by small lanceolate and ovoid scales evenly distributed, but concentrated into dense patches on uppermost parts of ventrites; 3 rd to 5 th abdominal ventrites with few isolated long setae on lateral thirds only; last visible ventrite with several rows of moderately short, adpressed setae along its apical margin; sutures between 2 nd to 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 13 separated bristles. Femora setose and moderately densely covered with lanceolate scales; tibiae with sparse lanceolate scales and spiniform setae; tarsi with setae only. Tarsomeres 1 – 4 shortened, especially of the fore tarsi; 1 st tarsomere of hind tarsi only slightly longer than 2 nd. Claws bifurcate, with lower lobe slightly closer to upper one than to base and almost parallel to upper one, distinctly shorter, but as broad as the latter.

GENITALIA. Aedeagus ( Fig. 5 A–B) strongly arcuate; phallobase conspicuously humped dorsally at its distal extremity; parameres almost uniformly deep along their length in lateral view, with apical extensions large, boot-shaped.

VARIATION. Length 14.0 mm, greatest width 5.5 mm. Margins of clypeus less angular than in holotype. Fronto-clypeal suture somewhat carinate in middle. Scales on dorsal surface of head, pronotum and elytra smaller and sparser than in holotype. Elytra with four costae more pronounced than in holotype. Abdominal ventrites more setose than in holotype.

Female

Habitus: see Fig. 3B . Length 16.0 – 17.0 mm, greatest width 6.5 – 7.0 mm. Fronto-clypeal suture concave in middle. Antennal club ( Fig. 4 D–E) consists of five antennomeres: 2 nd antennomere 1.4–1.7 times as long as 1 st (1 st antennomere sometimes only slightly exceeding anteromedial process of last antennomere of funicle in length), 2 nd antennomere one-third to two-thirds as long as 3 rd, 3 rd antennomere equal to or slightly shorter than 4 th; 4 th and 5 th antennomeres of equal length. Funicle: 4 th and 5 th antennomeres with conspicuous anteromedial process, 3 rd antennomere as long as 4 th and 5 th combined. Last maxillary palpomere more attenuated than in male. Scales on pronotum and especially on elytra unevenly distributed, intermixed with glabrous spaces forming a variegated pattern. Elytra with three–four more or less developed costae; humeral umbones conspicuously produced backward, with surface of elytra distinctly impressed behind them. Propygidium lacking long setae ( Fig. 4F ). Pygidium with glabrous medial stripe, sometimes callose on its basal half ( Fig. 4G ). Abdominal ventrites more inflated than in male. Protibial spur longer than in male. Apex of hind tibiae with 16 short, separated bristles. Tarsi shorter than in males; 1 st and 2 nd tarsomeres of hind tarsi equal in length.

Differential diagnosis

This new species is most similar to P. submaculata Heller, 1900 from northern Sulawesi in the possession of squamose vestiture (vs setose in P. jakli Zidek, 2018 and P. sulana Heller, 1900 ). Philacelota leucothea sp. nov. differs from P. submaculata in the following respects: long hair-like setae on the basal half of the propygidium very sparse in males and absent in females (vs dense in both sexes), much less callose pronotum and upper surface of the head, less costate elytra, and finer and sparser puncturation of their interstices. Furthermore, the males of P. leucothea sp. nov. differ from the males of P. submaculata in the elytra uniformly covered with scales (vs elytral costae glabrous), in the absence of the bare longitudinal stripe on the pygidium (vs present), and in the shape of the aedeagus ( Fig. 5 ).

Identification key for the species of Engertia and Philacelota

1. Antennal club with 5–7 lamellae in males and 4 or 5 lamellae in females, those of males conspicuously elongated; scales on elytral interstices aggregated into spots or stripes .............................. 2

– Antennal club with 3–5 lamellae in both sexes (rarely more than 3); when more than 3 in number, club lamellae not conspicuously elongated in males, and scales of elytral interstices never aggregated into spots or stripes ..........................................................other Indo-Australian leucopholine genera

2. Antennal club of males with 7 lamellae; 3 rd antennomere elongated in both sexes ( Fig. 6 B–D) ( Philacelota ) ...................................................................................................................................... 3

– Antennal club of males with 5 or 6 lamellae; 3 rd antennomere short in both sexes ( Fig. 6 A–C) ( Engertia )........................................................................................................................................... 6

3. Body vestiture squamose; parameres compressed laterally, with irregular outlines ........................ 4 – Body vestiture setose; parameres tube-like with expanded tips (unknown in P. sulana ) ................. 5

4. Upper surface of head and disc of pronotum with irregular callose areas of variable expression in both sexes. Males: basal half of propygidium with dense long setae; elytral costae glabrous; aedeagus as on Fig. 5 C–D. Females: basal half of propygidium with long setae; puncturation of the elytral interstices dense and coarse ( Indonesia: Sulawesi) ..................... P. submaculata Heller, 1900

– Upper surface of head and disc of pronotum with longitudinal callose stripe in both sexes. Males: basal half of propygidium with minute acicular and sparse long setae; elytral costae scaled; aedeagus as on Fig. 5 A–B. Females: basal half of propygidium with minute acicular setae; puncturation of the elytral interstices sparse and fine ( Philippines: Luzon) ...................................... P. leucothea sp. nov.

5. Protibiae unidentate in male; pronotum widest at base; setae of body vestiture very short and sparse ( Indonesia: Sula Mangoli) ................................................................................ P. sulana Heller, 1900

– Protibiae weakly bidentate in male; pronotum widest at midlength; setae of body vestiture long and dense ( Indonesia: Flores)...................................................................................... P. jakli Zidek, 2018

6. Antennal club with conspicuously elongated antennomeres. Males (unknown for E. maculosa ) .... 7

– Antennal club with short antennomeres. Females (unknown for E. allolepis sp. nov., E. germanica and E. papuana )............................................................................................................................... 12

7. Antennal club with 6 lamellae ( Philippines: Leyte, Palawan).................................. E. lii Keith, 2006

– Antennal club with 5 lamellae ........................................................................................................... 8

8. Scales heterogeneous in shape in two outermost interstices and along apical margin of elytra. Aedeagus more arcuate in profile and more robust in shape (as on Fig. 2G ) ( Indonesia: Ambon)..... .............................................................................................................................. E. allolepis sp. nov.

– Scales homogeneous in shape in all interstices and along apical margin of elytra. Aedeagus less arcuate in profile (except E. germanica ) and always more gracile in shape (as on Fig. 2J ).............. 9

9. Elytra covered with ovoid to lanceolate scales; scales present on labrum and metaventrite........... 10

– Elytra covered with setiform scales; labrum and metaventrite with setae only................................11

10. Elytra covered with ovoid scales; scales along midline of abdominal ventrites not aggregated into spots ( Indonesia: islands of Ambon, Yapen and Miosidi) .................... E. amboinae ( Brenske, 1897)

– Elytra covered with lanceolate scales; scales along midline of abdominal ventrites aggregated into small spots (New Guinea).......................................................................... E. papuana ( Moser, 1913)

11. Setiform scales on elytra thick; pygidium mainly setigerous; scales along midline of abdominal ventrites not aggregated into spots ( Indonesia: islands of Seram, Ambon and Saparua) .................... ..................................................................................................................... E. setifera ( Moser, 1913)

– Setiform scales on elytra thin; pygidium mainly scaly; scales along midline of abdominal ventrites aggregated into spots (New Guinea).................................................... E. germanica Prokofiev, 2016

12. Antennal club with 5 lamellae, first two abbreviated ( Philippines: Leyte, Palawan) ......................... .................................................................................................................................. E. lii Keith, 2006

– Antennal club with 4 lamellae, only first one abbreviated .............................................................. 13

13. Scales on elytra aggregated into spots; clypeus semicircular ( Sri Lanka)........................................... .............................................................................................................. E. maculosa ( Brenske, 1896)

– Scales on elytra aggregated into longitudinal stripes; clypeus polygonal ....................................... 14

14. Scales on elytra ovoid ( Indonesia: islands of Ambon, Yapen and Miosidi) ....................................... .............................................................................................................. E. amboinae ( Brenske, 1897)

– Scales on elytra setiform ( Indonesia: islands of Seram, Ambon and Saparua) ................................... ..................................................................................................................... E. setifera ( Moser, 1913)

Figures

Fig. 3. Philacelota leucothea sp. nov., habitus. A. ♂, holotype (MNHN). B. ♀, paratype (MNHN). Scale bars: 2.5 mm.

Fig. 4. Philacelota leucothea sp. nov., holotype, ♂ (MNHN) (A–C) and paratype, ♀ (MNHN) (D– G). A. Antenna, lateral view. B. Propygidium. C. Pygidium. D. Antenna, lateral view. E. Antenna, dorsolateral view showing relative size of club antennomeres. F. Propygidium. G. Pygidium. Scale bars: A, C–E = 1.5 mm; B = 2 mm; F–G = 2.5 mm.

Fig. 5. A–B. Philacelota leucothea sp. nov., holotype, ♂ (MNHN). A. Aedeagus, lateral view. B. Parameres, dorsal view. — C–D. P. submaculata Heller, 1900, from Kema, Sulawesi, ♂ (MNHN). C. Aedeagus, lateral view. D. Parameres, dorsal view. Scale bars: A–B = 1.5 mm; C–D = 2 mm.

Fig. 6. Shape of 3rd antennomere (arrowed) in males (A–B) and females (C–D) of the type species of the genera Engertia Dalla Torre, 1913 and Philacelota Heller, 1900. A, C. Engertia amboinae (Brenske, 1897). B, D. Philacelota submaculata Heller, 1900. Scale bars = 1.5 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.