Exolontha permirabilis, Keith & Pham & Sabatinelli, 2023

Keith, Denis, Pham, Phu Van & Sabatinelli, Guido, 2023, Exolontha permirabilis, a new species from Vietnam with notes on the genus (Col. Scarabaeidae Melolonthinae Melolonthini), Faunitaxys (Oxford, England) 11 (73), pp. 1-5 : 1-4

Exolontha permirabilis n. sp.

( Fig. 1, 4, 7, 10, 11 & 12)

ZooBank: https://zoobank.org/ 97151874-76CA-43A6-9AC0-C6988CBB9B61

Holotype, ♂, // Vietnam, Yên Bái Prov. / Nậm Có , 1500m / V.2023, local collectors // ( MHNG).

Paratypes

- 1 ♀, same data as for the holotype ( MHNG) ;

- 1 ♂, // Vietnam / Yen Bai / IV.2023 / local collector leg. // ( DKPC) .

Reviewers:

Description of males

General morphology and coloration. – Holotype ( Fig. 1) and paratype ♂ 20 mm in length (23.5 mm including pygidium). Dull, brownish-black. Head and pronotum with long upright to sloping rufous hairs. Scutellum , elytra with broad V-shaped median fascicle and apical declivity covered with short, recumbent black pilosity, base of elytra with large triangular patch of dense yellowish pilosity of decreasing length, lateral margins and front of apical declivity with similar, but sparser and shorter pilosity. Mesosternum, metasternum and legs with long reddish hair. Sternites with similar setation, sparser in the center, sloping, denser on the sides.

Head. – Clypeus with sides weakly converging towards the anterior margin from the middle, subparallel at the base. Punctuation thick, dense, forming reticulations, well embedded on dull integument. Lateral and anterior margins slightly raised, this one straight, not emarginated. Clypeofrontal suture obsolete, slightly bisinuate. Vertex and forehead in the same plane as the clypeus, slightly convex in the center, with punctuation similar to that of the clypeus, slightly denser still. No trace of longitudinal carina. Strong ocular canthus, with thickened, blackish, erect pilosity, 5/6 of the length of the eye viewed from above.Frons and vertex longer than clypeus.

Antennae. – Black, consisting of 10 antennomeres, with 7-jointed club, scape elongated, antennomere II cylindrical, III very long, 4 times longer than article II, club shorter than basal antennomeres collectively ( Fig. 10). Last article of maxillary palps elongated, with a slightly depressed area occupying almost the entire dorsal surface.

Pronotum. – Greatest width situated behind the middle, with clear angularity in lateral view, lateral margins very strongly convergent towards the anterior angles which are barely visible, less strongly convergent towards the posterior angles which are straight and prominent. Lateral margins crenate, only slightly enlarged in the distal half, shiny. Posterior margin without clear border. Punctuation similar to that of the head on dull integument. Anterior margin not marginated.

Scutellum . –Triangular withrounded apex,wider thanlong, punctuation similar to pronotum, entirely obscured by erect black setation.

Elytra. – Four thin costae present, the third vestigial, visible behind the humerus. Juxtasutural costa convex, less punctate, visible up to the apical declivity of the elytra. Punctuation uniformly composed of shiny, fine, dense granules. Humeral callus strong, apical callus distinct.

Pygidium. – Very slightly convex, with truncated apex, bearing dense microreticulations, pilosity mostly black, recumbent, dense, long erect setae on margins, especially on the distal part.

Protibia. – External margin with two acute teeth, the apical one strong, slightly directed outward, the basal external margin straight with no trace of sinuosity or vestigial tooth. Upper surface of protibia with strong, irregularly dense, deep punctuation. Mesotibia and metatibia without transverse carina. Base of mesofemur and metafemur serrated.

Mesosternum and metasternum. – Both with dense reddish villosity. Mesosternum not protruding forward. Abdomen with a central depression, clearly less punctate than the lateral parts of the sternites, on which the punctuation becomes denser laterally, punctuation small. Sternites almost glabrous in the center, hairy laterally. No lateral macules.

Description of the female. – Paratype ♀ length 21 mm. General morphology very similar to the males. No sexual dimorphism of the antenna ( Fig. 10, 11). Styli genitalis ending with truncated apex and a long point directed medially almost at 90 degrees ( Fig.12).

Etymology. – From the Latin, meaning "very remarkable"

Relationships. – Of the species currently assigned to the genus Exolontha , only two species have elytra with a triangular lighter basal patch: E. tonkinensis Moser, 1913 , known from Laos, Myanmar, Thailand, Vietnam, China (Yunnan) and E. umbraculata ( Burmeister, 1855) largely distributed in China (Chongqing, Fujian, Guangxi, Guizhou, Hong Kong, Hunan, Sichuan).

- E. tonkinensis ( Fig. 2) differs from E. permirabilis n. sp. as follows: larger size (22-25 mm),clypeus with arcuate anterior margin, presence of 8 elytral costae, weaker basal spot on elytra, entirely rufous pilosity on scutellum and elytra, without black discal fascicles, stronger protibia, aedeagus with elongated, parallel parameres dorsally subparallel and acutely curved ventrally (Fig. 5 & 8).

- E. umbraculata ( Fig 3) differs from E. permirabilis n. sp. as follows: erect hair on the head, pronotum and elytra shorter, the colors of this pilosity less vivid and intense, giving the insect a general dull brownish aspect, antennae brown, lateral pronotal margin less angular, last article of the maxillary palps less elongated, aedeagus less enlarged dorsally and with a shorter apex laterally (Fig. 6 & 9).

Remarks

- The supraspecific position of some taxa ( E. aterrima Keith & Sabatinelli, 2012 , E. bhutanensis Frey, 1975 , E. chiangmaiensis Keith & Sabatinelli, 2012 , E. pennata (Sharp, 1876) , E. ringenbachi Keith, 2008 ) remains unclear at this time: they differ from other species by the presence of 9 strong elytral costae, including one or two incomplete, and a very different type of aedeagus. In general morphology, they are close to the genus Carlschoenherria Bezdek, 2016 , restricted to insular Asia and having parameres shaped differently.

- Carlschoenherria brenskei ( Nonfried, 1906) was described from China: "Ou-Hen, Nord-West-China") in the description compared to E. serrulata (Gyllenhal, 1817) : “ der Schönh.

1, 4 & 7. Exolontha permirabilis n. sp. 2, 5 & 8. E. tonkinensis Moser, 1913 . 3, 6 & 9. E. umbraculata ( Burmeister, 1855) .

serrulata am nächsten verwandt” and could ultimately be placed in the genus Exolontha . Its clypeus, however, is “merklich ausgebuchtet”, which is enough to exclude it. The position of this taxon therefore remains enigmatic in the absence of a type until now not traced, it could ultimately relate to the genus Tocama Reitter, 1902 , but it is certainly not a Carlschoenherria as listed in Bezděk (2016), by virtue of its distribution and by characters mentioned in the description.

- Exolontha serrulata (Gyllenhal, 1817) has been reported from the Philippines. In fact, Blanchard (1850) described Melolontha manillarum from there and later, Burmeister (1855) synonymized this species with E. serrulata , already questioning the Philippines as its patria [in China (und auf den Philippinen?)]. But Baer (1886) continued to mention E. serrulata from there. In the absence of any available specimens from the Philippines, we can consider records from Philippines unsubstantiated and doubtful.

- E. laticauda ( Bates, 1891) and E. neofuliginosa Ahrens, 2019 (replacement name for E. fuliginosa (Fairmaire, 1889)) both described from Sichuan, have never been revised and might be identical to some species later described by Y.W. Zhang (1965, 1980, 1981 and 1992).