Psilopholis vietnamensis, Reichenbach & Keith, 2023

Psilopholis vietnamensis spec. nov.

(1& 2)

ZooBank:http://zoobank.org/ 9681E2B2-EF4C-4892-A8B9-AC0B2D824A8C

Holotype, ♂, Vietnam, Quang Nam, Tay Giang, MtAxan , 1300m, IV. 2017, local collector leg (ex DKCC, to be deposited in MNHNP) .

Paratypes

- 3 ♀ (1 designated as Allotype) Vietnam, Quang Nam, Tay Giang, Mt Axan , IV. 2017, local collector leg ( DKCC) ;

- 4 ♂ & 6 ♀, Vietnam, Quang Nam, Tay Giang, Mt Axan , III. 2018, Van Dang leg ( DKCC) ;

- 1 ♂ & 2 ♀, Vietnam, Quang Nam, Tay Giang, Mt Axan , 1300m, VII. 2021, Tranh leg ( DKCC) ;

- 3 ♂ & 4 ♀, Vietnam, Quang Nam, Tay Giang, Mt Axan , 1700m, VII. 2021, Tranh leg ( DKCC) ;

- 1 ♂ Vietnam NgocLinh 1700m, Kon Tum, VI 2016, local collector leg ( ARCL) ;

- 1 ♀ Vietnam, Quang Nam, Tay Giang, Mt Axan , IV. 2017, local collector leg ( ARCL)

Description of the holotype

Length 29 mm. – Body large and elongate. – Dorsal and ventral surface brown toreddish brown and almost completely coveredwith short more or less adpressed to reclined yellowish-grey to yellowish-brown hairs ( Fig. 1 View Fig ).

Head. – Clypeus subquadrate, reflexed anteriad, straight,shortly rounded at the antero-lateral corners. Clypeus and frons covered with hairs. – Punctuation all-over coarse and irregular, dense, the limits between punctures forming vermiculations of the integument. – Integument dull. – Antennae with 10 antennomeres, club 3-lamellate,which is longer than antennomeres 2-7 together.

Pronotum. –Very transverse,convex,stronglynarrowed anteriorly. – Lateral margin very slightly sinuate in anterior half and serrate throughout; base projectingmedially on scutellum. – Anterior angles slightly protruding, posterior angles marked, protruding backwards. – Punctation of the same type as on the head but distinctly smaller with the integument forming a very tight network of vermiculations between the numerous and dense points, shinier.

Scutellum. – With punctuation and vestiture as on pronotum.

Elytra. – Smooth, with veryobsoletetohardly evident costae, witha distinct sharply raised apical callusclothed witha tuft of longer hairs. – Humeral callus strongand very distinct. – Punctuation as on pronotum but much smaller with more free areas of integument between, giving a brighter appearance.

Pygidium. – Covered with short hairs, similar to those on pronotum and elytra.

Underside. – Prosternum with triangular postcoxal process. – Metasternum and metacoxae shining, densely covered with long hairs. – Sternites smooth, densely covered with very short hairs throughout; presence of scattered pupillate punctures in the center of a small smooth area contrasting with the surrounding surface.

Legs. – Protibia with three denticles, the third denticle situated nearly medially and slightly offset toward the base, shorter than the others but obvious. – Metafemur densely covered with short hairs; longer metatibial apical spur sharp, pointed apically and not definitively longer than he 1 st metatarsal segment.

Aedeagus ( Fig. 2 View Fig ). – Parameres almost straight and parallel from above, forming an Omega-shaped end in sideview.

Female ( Fig. 1 View Fig ). – Closely resembling male in almost all respects. Antennal lamellae somewhat shorter, metafemur a little wider, and protibial denticles more rounded than in the male.

Derivatio nominis. – As a reference to the geographic origin of the species.

Variability. – The series is rather homogenous and length varies from 27 - 30 mm (mean 28.3 mm) for males and 29 - 33 mm (mean 30.1 mm) for females.

Discussion. – Aside its very distinctive genitalia, this new species can readily be discriminated from the others by its size, the sternites pilose and punctured all-over, the elytra with hardly visible costae and the size of the antennal club longer than the funicle without the scape.

Remarks. – The melolonthine genus Psilopholis has been introduced without any real generic characterization by Brenske (1892): und zwar bildet grandis [Lepidiota] eine eigene Gattung, die ich Psilopholis nenne, wohin auch vestita Sharp gehört.

In fact, he will give a justification later ( Brenske, 1894a): Die vorliegende Art [ =grandis ] gehört unzweifelhaft zu den Leucopholiden und nicht zu den Rhizotrogiden , und wer meiner Ansicht nicht ist, für diese und vestita eine neue Gattung aufzustellen, möge sie unter Lepidiota wohin sie Redtenbacher stellte, belassen, und sie nur als eine behaarte Art von den beschuppten absondern. Meine Gründe aber für die Trennung alsGattung sind die folgenden. Allgemein: Der habitus ist nicht mehr der einer Lepidiota, die Gestalt ist schlank, die Schuppen, welche allen Mitgliedern eigen sind fehlen ganz, und die Geschlechtsunterschiede kommen in anderer Weise hier zum Ausdruck. Das letztere hebt schon Burmeister hervor, welcher angiebt, dassder Fächer des ♂ und ♀ gleich gross sei.Es ist einsehrgeringer Unterschied nur vorhanden, auch ist der weibliche Schienbeinsporen nur wenig breiter als der männliche und die Schienen selbst sind an der Spitze beim ♀ nur mässig erweitert. Dafür tritt hier ein neues Geschlechtsmerkmal auf, welches bei den anderen Lepidioten nicht beobachtet ist:

Das ♀, hat auf dem letzten unteren Hinterleibsringe einen Quereindruck, der dem ♂ fehlt; hieran sind die beiden Geschlechter sehr leicht zu erkennen.

Specielle Merkmale: Das entscheidende ist hier die Bildung der Hinterbrust. Bei den Lepidioten entsendet diese nach vorn einen Fortsatz, welcher sich zwischen die Mittelhüften einschiebt und sich hier mit dem Fortsatz der Mittelbrust verbindet; die Verbindungsstelle ist immer durch eine glatte Naht, welche der Spitze nahe gerückt ist, angedeutet.Beiden Lepidiotenmüsste man daher correctervon einem Fortsatz der Hinterbrust sprechen, statt von einem solchen der Mittelbrust, denn jene ist stärker an dieser Bildung betheiligt (*).

Bei der vorliegenden Gattung nun dehnt sich die Hinterbrust nicht nach vorn aus, sie schiebt sich nicht zwischen die Mittelhüften, sondern schliesst hinter denselben deutlich ab und die Mittelbrust schiebt den schmalen Verbindungstheil zwischen die Hüften. Die VorderschienensindinbeidenGeschlechternscharfdreizahnig.

Arrow (1938) evidently overlooked this definition and pointed to this problem, although providing some noticeable characterization: This insect, called Trichopholis vestita by Sharp, was placed by Brenske, together with grandis Cast. , under the catalogue name Psilopholis , to which no characters have ever been assigned. The proportions differ considerably from those of Trichopholis. The head is relatively small, the pronotum shortand broad, with well-marked hind angles, and the elytra are long. The middle coxae in these two genera are not separated by a mesosternal process and the clothing does not consist of flat scales, but of short close-lying setae.

Matsumoto (2010) provided a definition in a modern sense but without any reference to Brenske (1894a): Body moderately to extremely large, elongate and convex. Both dorsal and ventral surfaces densely covered with thick minute hairs, without any roundish or oval scales. Clypeus quadrate, gently rounded at antero-lateral corners, with anterior margin straight; antennae 10-segmented with three small lamellae; mentum transverse and pot-shaped with lateral margin strongly emarginate in anterior half.

Prosternum with triangular process just posterior to the intercoxal space of pro-coxae; mesosternum without any intercoxal process. Lateral sides of abdominal sternites each devoid of whitish patches of short thick hairs.

Protibia with three distinct denticles; the 2nd denticle clearly approaching to the 1st one; 3rd denticle rather sharp.

Aedeagus depressed and wide; phallobase twice as long as or longer than parameres in dorsal view, widely cleft and gently concave in each of apico-lateral triangular portions.

In the course of his study, Masumoto (2010) also synonymized Tricholepis vestita Sharp, 1881 with P.grandis ( Castelnau, 1840) after he carefully read SHARP’ soriginaldescriptionofhis Tricholepis vestita . It agrees well with the female characteristics of Psilopholis grandis .

Up to now, we couldn’t trace Sharp’s typical series of 4 specimens caught on Java and Sumatra. But after examination of different specimens from Malaysia and Indonesia, we can’t agree with this treatment: there is a widespread taxon with medially smooth sternites in both sexes which fits well Sharp’s description as well as Brenske’s comments later. Furthermore, it shows distinctive genitalia, very different from both P. grandis and P.gigantea Masumoto, 2010 : we refer it to Psilopholis vestita Sharp, 1881 stat. rest., bona species.

The distribution of the hitherto known species appears to be centred on the Sunda islands; all of them are found on Borneo, and both P. grandis and P. vestita were (and are) additionally collected on Java and Sumatra (incl. Nias). Only the new species, P.vietnamensis , is restricted to the Asian mainland. The real distribution of P.grandis and P.vestita , however, remains to be elucidated. One reason for that is the probable confusion of the two species by Brenske (1892) which makes it impossible to use his distribution data as reliable ( Arrow 1938), though largely used by Dalla Torre (1912).

In the case of P. grandis, Blanchard (1845) wrote “Le type of du genre Ancylonycha ( A. pubera, Dej. ) provient de l’île de Java ” [ A. pubera = P.grandis ]; Arrow (1938) “believe[d] it to be confined to Java ”, and Balthasar (1932) also listed P. grandis from Java, Buitenzorg , 1928. We can confirm its occurrence in Java, and also in Sumatra ( Utara ), Nias and Borneo .

In addition, Brenske (1892), as well as Dalla Torre (1912), records the species from the Philippines (Manila) and Amboina ( Ambon Island). Whereas we have been unable to find a verifiable source for the latter, a specimen from the Philippines was described as Leucopholis (Lepidiota) manillae by Redtenbacher (1868), and synonymized with P.grandis by Brenske (1892). We could examine HD-pictures of the (female) type of Redtenbacher’s species and its patria label, kindly provided by H. Schillhammer, Wiener Hofmuseum, Vienna ( Fig. 3 View Fig ). Both the photos and the original description of the specimen (particularly, “ Bauchringe sehr fein schuppenartig punktiert ...”) fit to the features of P.grandis ; furthermore, the patria label gives the name of the responsible zoologist (Zelebor) and of the expedition (Novara) as well as that of the species ( manillae ).

Indeed, in 1858 two consecutive stations of the Novara expedition were Java and Manila. If there had been no confusion of the sites and the name was given on the basis of the real patria, this means that P.grandis occurred in Manila, at leastat the time of the Novara expedition. Unfortunately, neither Matsumoto (2010) nor one of the authors or the entomologist colleagues they asked ever saw a specimen undoubtedly collected on the Philippines (or on Ambon Island). Thus, either the distribution of the species got narrowed within the century after the description of L. (L.) manillae , the least likely hypothesis, or both Manila and Ambon need to be considered as patria falsa.

Likewise, we found no reliable collection data of any species from the Asian mainland, including West Malaysia (Penang and Malacca). Therefore, all previously known taxa are restricted to insular Asia.

Another question is that of the classification of the genus into one of the current tribes of Melolonthinae . Conventionally, the genus is assigned to the Leucopholini or Leucopholina , respectively (cf. e.g. Brenske, 1892). A similar genus of ‘scale-devoid but hairy, large’ species, Alepida Allsopp (2018) (sorted out from Lepidiota Kirby) would also belong to the “classical Leucopholini ” because the antennae are 3-lamellate as in Psilopholis . There are other genera with ‘scale-devoid but hairy, large’ species which classically are considered as “ Melolonthini ” such as Rhopaea Erichson (antenna 5- to 8-lamellate; lamellae much longer in the male than in the female) ( Britton 1957b), and scale-devoid species of Dermolepida Arrow (male antenna 5-lamellate, female 4-lamellate) ( Britton 1957a, b). Noteworthy, Britton (1957 b, 1978) does not discriminate between the two classical tribes but assigns Lepidiota as well as Rhopaea and Dermolepida to “ Melolonthini ”.

This position, which might seem innovative, is in fact based, in his own words, on essentially practical and not analytical reasons: The object of this work is to prove a means of identifying Australian Chafers ( Britton, 1957), then It would indeed have been most satisfactory to have started the revision with a classification based on a study of the Melolonthinae of the world. This would, however, have been in itself a major work and would have precluded the achievement of my objective, which was primarily to make the Australian species identifiable ( Britton, 1978).

In a recent molecular analysis (Eberle et al., 2018) Dedalopterus fujianensis (Zhang) and Psilopholis grandis (Cast.) – both traditionally assigned to “ Leucopholini ” – are placed close together but clearly distant from “ Leucopholina ” and “ Melolonthina ” in a tree displayed to elucidate the phylogeny of Melolonthine chafers. Thus, as already suggested by Matsumoto (2010), probably the taxa “ Melolonthina ” and “ Leucopholina ” cannot be maintained without redefinition in future.