Research Article |
Corresponding author: Hendrik Freitag ( hendrik.freitag@gmx.de ) Academic editor: Mariano Michat
© 2018 Hendrik Freitag, Clister V. Pangantihon, Iva Njunjić.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Freitag H, Pangantihon CV, Njunjić I (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. https://doi.org/10.3897/zookeys.754.24276
|
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 G. 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.
André Kuipers, Leonardo DiCaprio, new species, riffle beetle, taxon expeditions, taxonomy, Quest magazine
During the first biodiversity discovery field course for citizen scientists, termed “taxon expedition” (
Citizen Science initiatives in biodiversity research have become increasingly popular with an estimated annual growth rate of 10% in number of projects launched (
Since basic research on invertebrates (including taxonomy and faunistics) is relatively infrequent and underfunded (
This paper deals with three new species of the genus Grouvellinus Champion, 1923. The genus, named in honour of the French coleopterologist Antoine Henri Grouvelle (1843–1917), comprises small to medium-sized riffle beetles (Elmidae) of dark (usually black), or rarely cupreous colour and is distributed in the Oriental and Palaearctic regions from Samos (Greece) in the west up to Japan in the East and Java (Indonesia) in the south (
The specimens were collected by taxon expedition participants and instructors using small-meshed hand-nets and preserved in 96% ethanol. After return to the field station, participants sorted the collected specimens to genus level under a Nikon SMZ445 stereomicroscope with 20 × oculars (allowing magnification up to 70 ×) and with the help of provided taxonomic literature. Microforceps, insect pins, and the same optical equipment were subsequently used for the dissection of specimens and the detailed material examination. This step was carried out by the participants only for morpho-species of which larger series were available, while the instructors handled single records of new species to limit damage through unexperienced handling of potential holotypes. Diagnostic characters of the external habitus and the genitalia were briefly recorded by the participants.
Photographs of dissected parts were taken from temporary slides in lactic acid under an Olympus CX compound microscope. Preliminary photographs of the dorsal habitus of entire specimens (as used in the public species-naming contest) were obtained by the participants using a Canon EOS 500D with MP-E 65 mm lens attached to a Kaiser stand with vertical micro-adjustment drive. Series of vertical photographs series were taken and layers were subsequently stacked using CombineZP software.
After the actual field course, CorelDRAW Version 10.0 software was used by the authors to compile digital line drawings. Additional high-quality photographs were taken under a Zeiss Axio zoom V 16 microscope with Canon 5D SLR camera using diffuse LED lighting. Images were captured at various focus layers and subsequently stacked using the Zerene Stacker software.
Morphological terminology used herein mainly follows the Elmidae chapter of the Handbook of Zoology/Coleoptera (
The following abbreviations were used:
a.s.l. above sea level (elevation)
CL calculated length (PL + EL)
EL elytral length, measured along the elytral suture from basis to apex
EW maximum elytral width
HW head width, including eyes
ID interocular distance
PW maximum pronotal width (at posterior portion)
PL pronotal length
All collected material is deposited at the Borneensis Coleoptera Collection (
Malaysia, Sabah (Eastern Borneo Island), Maliau Basin, upstream Giluk Falls, ca. 4°44'49"N, 116°52'38"E, ca. 950 m a.s.l. (Fig.
Holotype ♂ (
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.
Body obovate, 2.97 mm long (CL), 1.60 mm wide (EW), 1.9 times as long as wide (CL/EW).
Dorsal colouration (Figs
Head 0.65 mm wide (HW); ID 0.27 mm; partly retractable; labrum with dense fringes of moderately long setae, punctures very small and dense; frons and clypeus moderately pubescent, setae moderately long, punctures small and moderately dense; intervals almost flat and glabrous. Frontoclypeal suture distinct, slightly concave. Eyes moderately protruding. Antennae genus-typical, slightly shorter than HW.
Pronotum (Fig.
Prosternum (Fig.
Scutellum (Fig.
Elytra (Figs
Mesoventrite (Fig.
Metaventrite (Fig.
Abdominal ventrites (Fig.
Legs (Fig.
Aedeagus (Fig.
Male sternite IX (‘spiculum gastrale’) with posterior margin rounded and entirely fringed with a broad, distinctly sclerotized margin; paraprocts closely attached to posterior portion, sub-equally long, not reaching apical margin; median strut broken and not examined.
Grouvellinus leonardodicaprioi sp. n. (holotype male): A aedeagus in lateral view (spines of ventral sac omitted) B aedeagus in ventral view (spines of ventral sac omitted) C microscopic photograph of aedeagus in lateral view optically emphasizing the dense distribution of internal and external spines of the ventral sac. Scale bar: 0.1 mm.
Unknown.
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.
This species is only known from the type locality, the Giluk Falls of the upper Maliau Basin, Sabah (Figs
Malaysia, Sabah (Eastern Borneo Island), Maliau Basin, Creek east of ‘Nepenthes Camp’, ca. 4°44'57"N, 116°52'45"E, 1000 m a.s.l. (Fig.
Holotype ♂ (
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.
Body elongate obovate, 1.5–1.8 mm long (CL), 0.73–0.85 mm wide (EW), 2.1 times as long as wide (CL/EW).
Dorsal colouration (Figs
Head 0.35–0.37 mm wide (HW); ID 0.14–0.21 mm; partly retractable; frons, clypeus, and labrum sparsely pubescent, slightly denser laterally; punctures small and scattered; intervals flat, glabrous. Frontoclypeal suture almost straight. Eyes very slightly protruding. Antennae genus-typical, rarely exposed, usually semi-circularly folded around anterior eye margin.
Pronotum (Fig.
Prosternum (Fig.
Scutellum (Fig.
Elytra (Figs
Mesoventrite (Fig.
Metaventrite (Fig.
Abdominal ventrites (Fig.
Legs (Fig.
Aedeagus (Fig.
Male sternite IX with median strut moderately long and almost rectangularly bent sub-distally; posterior portion entirely fringed with a broad, distinctly sclerotized margin; posterior margin rounded; paraprocts sub-equal in length, not reaching apical margin.
Ovipositor (Fig.
The paratypes from Brunei are among the smallest specimens within the given measurement ranges and have a somewhat smoother elytral surface with less impressed punctures and less elevated carinae; the aedeagus agrees well in the distinctive features (shape, size and setation of parameres; shape and size of median lobe), but the phallobase is slightly longer (0.67 of total aedeagus length), slightly slenderer and more ventrally bent basally. In specimens from either locality, elytra and pronotum are commonly incrusted with deposits making proper examination of the surface structure hardly possible.
Unknown.
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
This species is known only from Borneo Island, namely the upper Maliau Basin in Sabah and two sites in Brunei (Fig.
Malaysia, Sabah (on Borneo Island), Maliau Basin, upstream Giluk Falls, ca. 4°44'49"N, 116°52'38"E, ca. 950 m a.s.l. (Fig.
Holotype ♂ (
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.
Body elongate obovate, 1.7–1.8 mm long (CL), 0.86–0.91 mm wide (EW), 2.0 times as long as wide (CL/EW).
Dorsal colouration (Fig.
Head 0.35–0.39 mm wide (HW); ID 0.16–0.17 mm; partly retractable; frons, clypeus, and anterior and lateral areas of labrum moderately pubescent; punctures small; intervals medially flat and glabrous, laterally rugulose. Frontoclypeal suture straight, indistinct. Eyes slightly protruding. Antennae genus-typical, usually semi-circularly folded around anterio-lateral eye margin.
Pronotum (Fig.
Prosternum (Fig.
Scutellum sub-triangular, medially slightly impressed, glabrous.
Elytra (Fig.
Mesoventrite (Fig.
Metaventrite (Fig.
Abdominal ventrites (Fig.
Legs (Fig.
Aedeagus (Fig.
Male sternite IX as in previous new species.
Ovipositor (Fig.
Unknown.
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.
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.
We would like to thank Taxon Expeditions participants and instructors Menno Schilthuizen, Carin Bondar, Massimo Delledonne, Mary Erickson, Lilian Seip, Sean Otani, Corlijn de Groot, Paolo Piccoli, and Paul Serail for assistance in the field, Jadda Suhaimi and staff at Maliau Basin Studies Centre for support, Liew Thor Seng, Charles Vairappan, Junn Kitt Foon, and Yeong Kam Cheng of Universiti Malaysia Sabah for assistance in databasing and collection deposition. Thanks are also due to Angelito Felipe L. Puno (Quezon City, Philippines) for the digital improvement of habitus pictures and line drawings. This research was carried out under SaBC access licence No. JKM/MBS.1000-2/2 JLD.5 (51) and under Maliau Basin Management Committee permit YS/MBMC/2016/245. The participation of the second author was partly funded by an Ateneo de Manila University Internationalization Grant.