Tuesday, May 1, 2018

[Entomology • 2018] Grouvellinus leonardodicaprioi, G. andrekuipersi & G. quest • Three New Species of Grouvellinus Champion, 1923 (Coleoptera, Elmidae) from Maliau Basin, Sabah, Borneo, discovered by Citizen Scientists during the First Taxon Expedition

Grouvellinus leonardodicaprioi
Freitag, Pangantihon & Njunjić, 2018

Further results are presented of the first field course at Maliau Basin, Malaysian Borneo organized by Taxon Expeditions, an organization which enables citizen scientists to be directly involved in taxonomic discoveries. Three new species of the aquatic beetle genus Grouvellinus Champion, 1923, namely Grouvellinus leonardodicaprioi sp. n.G. andrekuipersi sp. n., and G. quest sp. n. were collected jointly by the citizen scientists and taxonomists during the fieldwork in Maliau Basin. Material was mainly sampled from sandstone bottom rocks of blackwater streams at altitudes between 900 m and 1,000 m using fine-meshed hand-nets. The genus is widely distributed in the Oriental and Palearctic regions, but these are the first records from the island of Borneo.

Keywords: André Kuipers, Leonardo DiCaprio, new species, riffle beetle, taxon expeditions, taxonomy, Quest magazine

Figures 2–4. Habitus of the new Grouvellinus species collected from the Maliau Basin:
Grouvellinus leonardodicaprioi sp. n. (image of holotype male partly complemented) 3 G. quest sp. n. (paratype male from ‘NepC3g’) 4  G. andrekuipersi sp. n. (paratype male from ‘NepC3g’). Scale bar: 1 mm.

Genus Grouvellinus Champion, 1923

Grouvellinus leonardodicaprioi sp. n. (image of holotype male partly complemented).  Scale bar: 1 mm. 

Grouvellinus leonardodicaprioi sp. n.

Type locality: Malaysia, Sabah (Eastern Borneo Island), Maliau Basin, upstream Giluk Falls, .., ca. 950 m a.s.l. (Fig. 12A)

Etymology: The new species is named in honour of the actor Leonardo DiCaprio to acknowledge his inspiring work in promoting environmental awareness and bringing the problems of climate change and biodiversity loss into the spotlight. The species name was selected during a naming ceremony at Maliau Basin Studies Centre on 6 October 2017, in which expedition participants as well as a large number of field centre staff and porters took part.

Differential diagnosis: By its unusually large size, Grouvellinus leonardodicaprioi sp. n. resembles G. hercules Jäch, 1984 from Nepal, which also shares some other characters with the new species (only 7th and 8th elytra interval crested, margins of prosternal process fringed, elytral apices pointed), but G. leonardodicaprioi, sp. n. can be distinguished by the slenderer elytra, the fully glabrous (in between punctures) and not elevated median pronotum, the shallower elytral striae, as well as by its conspicuously varying aedeagus with broad main piece which distinctly overreaches the evenly rounded paramere tips (vs. very slender main piece only slightly overreaching the conically tapered paramere tips in G. hercules). The large size and other characters mentioned above also allow clear distinction from the species described below and any known congeners from Malaysia and Indonesia.

Distribution: This species is only known from the type locality, the Giluk Falls of the upper Maliau Basin, Sabah (Figs 11, 12A).

Grouvellinus quest sp. n.

Type locality: Malaysia, Sabah (Eastern Borneo Island), Maliau Basin, Creek east of ‘Nepenthes Camp’, .., 1000 m a.s.l. (Fig. 12B).

 Etymology: The species epithet refers to the English noun ‘quest’ (search, aspiration) in reference to the intense search for riffle beetles at Maliau Basin which was a big quest for the citizen scientists involved in the project. Additionally, the new species is named for the Dutch popular science magazine QUEST of which journalist Paul Serail joined the first taxon expedition. The word is used as a noun in apposition.

Differential diagnosis: Grouvellinus quest sp. n. superficially resembles the Indonesian species G. aeneus (Grouvelle, 1896), but it is slightly larger (CL: 1.5–1.8 mm vs. total length 1.5–1.7 mm), black (vs. brown), and the pronotal disc is flat between punctures (vs. shagreened). Based on the only available undamaged male material of G. aeneus (see Jäch 1984; NMW: “Bali Baturiti D. Limnol. Exp.”) that was, however, not determined with absolute certainty, there are distinct differences in their aedeagi: larger (550–560 μm long), with longer phallobase (> half total length) and with sub-globular, ventrally bent tip of the median lobe in G. quest sp. n. (vs. smaller (400 μm long), with shorter phallobase (< half total length) and regularly rounded tip of median lobe in G. aeneus). G. quest sp. n. and all other new species treated in here can easily be distinguished from the only know Malaysian species G. bishopi by the absence of a median pronotal carina.

Distribution: This species is known only from Borneo Island, namely the upper Maliau Basin in Sabah and two sites in Brunei (Fig. 11).

Grouvellinus andrekuipersi sp. n.

Type locality: Malaysia, Sabah (on Borneo Island), Maliau Basin, upstream Giluk Falls, .., ca. 950 m a.s.l. (Fig. 12A).

Etymology: The new species is named after the Dutch astronaut André Kuipers in recognition of his engagement against the loss of the planet’s natural resources and his ambassadorship for various entomological organizations. The name was elected in an online public contest organized by the science program De Kennis van Nu of the Dutch public broadcaster NTR.

Differential diagnosis: Grouvellinus andrekuipersi sp. n. is similar in size, pronotal and elytral surface structure to G. thienemanni Jäch, 1984 and G. sumatrensis Jäch, 1984, but displays a slenderer pronotum in relation to the elytra and slightly convex lateral elytral margins (vs. slightly concave or straight in basal half in G. thienemanni and G. sumatrensis). The yellowish elytral patterns commonly seen in G. andrekuipersi sp. n. were not observed in any examined specimen (n = 20) of the two congeners. Their entire elytra and pronotum appear overall slightly paler (brown). Additionally, the pronotal basis is entirely rugulose (“shagreened”) in G. thienemanni and G. sumatrensis (vs. glabrous with a pair of median rugose patches in G. andrekuipersi sp. n.). In G. thienemanni, the pronotal disc is additionally more densely punctate. The aedeagus of the new species is also similar in size and proportions to that of G. thienemanni, but in G. andrekuipersi sp. n., the paramere tips are distinctly conical (vs. evenly rounded in G. thienemanni) and the median lobe is wider and conically tapering towards apex (vs. evenly slender in apical 1/5 in G. thienemanni). From the previous new species (G. quest sp. n.), G. andrekuipersi sp. n. can easily be distinguished by 1) the pale elytral patches; 2) the smoother elytral surface due to the lack of any other elytral carinae than at interval 8; 3) the relatively broader and laterally convex elytra; 4) the sparse punctures of the pronotum; and 5) the smaller aedeagus with distinctly varying base, median lobe, and parameres.

Distribution: This species is known only from Borneo Island, namely the upper Maliau Basin, Tawau Hills Park, and Crocker Range in Sabah and two sites in eastern Sarawak (Fig. 11).

Figure 11. Map of the eastern tip of Borneo with large parts of Sabah, Malaysia and Negara Brunei Darussalam and the collection sites of the new Grouvellinus species (additional paratypes from NMW) and enlarged area of the Maliau Basin with collection sites of the first taxon expedition. 

Figure 12. Type localities of the new species: A Giluk Falls (for Grouvellinus leonardodicaprioi sp. n. and G. andrekuipersi sp. n. B Creek east of ‘Nepenthes Camp’ (for G. quest sp. n.).

Hendrik Freitag, Clister V. Pangantihon and Iva Njunjić. 2018. Three New Species of Grouvellinus Champion, 1923 from Maliau Basin, Sabah, Borneo, discovered by Citizen Scientists during the First Taxon Expedition (Insecta, Coleoptera, Elmidae).  ZooKeys. 754: 1-21.  DOI: 10.3897/zookeys.754.24276