Research Article |
Corresponding author: Ján Kodada ( jan.kodada@uniba.sk ) Academic editor: Lyubomir Penev
© 2022 Ján Kodada, Manfred A. Jäch, Dávid Selnekovič, Katarína Goffová.
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:
Kodada J, Jäch MA, Selnekovič D, Goffová K (2022) Okalia necopinata sp. nov. (Insecta, Coleoptera, Elmidae) from Gunung Mulu National Park in Sarawak (Malaysia). ZooKeys 1092: 79-92. https://doi.org/10.3897/zookeys.1092.79635
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Okalia necopinata sp. nov., from Sarawak, northwest Borneo, Malaysia, is described and illustrated along with an identification key. The standard barcoding fragment of the mitochondrial gene coding for cytochrome c oxidase subunit I (COI) was used together with morphological characters to delimit the taxonomic boundaries of the two known species, which live in shallow streams flowing through dense primary forests in limestone areas in Pahang (West Malaysia) and Sarawak (East Malaysia). The majority of all examined Okalia are flightless. Morphological distinguishing characters are the length of the granulated fifth elytral interval, the elytral and pronotal punctation, the aedeagal morphology, and the distal portion of the ovipositor.
Barcoding, Borneo, DNA, Dryopoidea, Macronychini, Oriental Region, riffle beetles, taxonomy
The island of Borneo is known for its exceptionally diverse fauna, currently surviving mainly in regions still covered by primary forests. A faunistic survey on the diversity of Elmidae and Dryopidae in the Malaysian state of Sarawak (nortwest Borneo) was carried out by Ján Kodada and Dávid Selnekovič in 2018 and 2019.
Some of the best-preserved biotopes are located in Gunung Mulu National Park, which has an area of 544 km2 and a wide range of rainforest, soils, and types of running water.
Sampling in a small stream meandering through lowland forest yielded an interesting assemblage of riffle beetles, including, for instance, specimens of Ancyronyx Erichson (
So far, one species of Okalia, O. globosa Kodada & Čiampor, has been described. This species is known from the type locality in the Malaysian state of Pahang (
Specimens were immediately preserved in 96% ethanol, specifically for the use of DNA barcoding.
The material examined is deposited in the following collections:
CFDS Forest Department Sarawak, Kuching, Malaysia;
CKB Collection Kodada, Comenius University, Bratislava, Slovakia;
Dried type specimens of Okalia globosa were relaxed in warm water with several drops of concentrated acetic acid and cleaned. Detached abdomina were exposed to lactic acid for 1–2 days and temporarily mounted in Berlese’s fluid on a cavity slide covered with a cover glass.
Specimens were examined and measured using a Leica M205C stereomicroscope with fusion optics and diffuse lighting at magnifications up to 160×. Measurements were made with an eyepiece graticule (5 mm: 100) or a Leica MC190-HD camera attached to the microscope and LAS software. The specimens were photographed with a Zeiss Axio-Zoom.V–16 stereomicroscope using diffuse LED lighting and a Canon 5D Mark IV camera attached. Each stacked microphotograph was created by stacking 100–120 focal planes with the image-stacking software ZereneStacker (https://zerenesystems.com/cms/stacker). Dissected genitalia and pregenital segments were studied and drawn at magnifications up to 640× with a Leica DM 1000 microscope and a Leica drawing device. In several specimens, one elytron was removed in order to confirm the absence of hind wings. The morphological terminology follows
The following morphological characters were measured:
BL body length without head, length of pronotum and elytra measured along midline;
EL elytral length, measured along suture from the level of the most anterior point to the most posterior tip in dorsal view;
EW maximum elytral width;
MW maximum pronotal width;
PL pronotal length along midline.
Nine specimens of O. necopinata and two exemplars of O. globosa stored in 96% ethanol were used for molecular analyses. A tissue sample contained either one leg with coxa and attached muscles or the entire (divided) adult specimen. DNA was isolated with the E.Z.N.A. Tissue DNA kit (OMEGA Bio-tek Inc., Norcross, GA, USA) or the DNeasy Blood and Tissue Kit (Qiagen, Hilden, Germany) according to the manufacturer’s protocol. The fragment of the 5' end of the mitochondrial gene coding for cytochrome c oxidase subunit I (COI) was amplified with primers LCO1490 and HCO2198 (
Specimens, voucher IDs | Origin | GenBank no. | BOLD ID no. |
---|---|---|---|
Okalia necopinata JK097 | Malaysia, Sarawak, Gunung Mulu | MT667271 | BOLD:AEE6243 |
Okalia necopinata JK001 | Malaysia, Sarawak, Gunung Mulu | MT667272 | BOLD:AEE6243 |
Okalia necopinata JK201 | Malaysia, Sarawak, Gunung Mulu | MT667273 | BOLD:AEE6243 |
Okalia necopinata JK203 | Malaysia, Sarawak, Gunung Mulu | MT667274 | BOLD:AEE6243 |
Okalia necopinata JK205 | Malaysia, Sarawak, Gunung Mulu | MT667275 | BOLD:AEE6243 |
Okalia necopinata JK207 | Malaysia, Sarawak, Gunung Mulu | MT667276 | BOLD:AEE6243 |
Okalia necopinata JK206 | Malaysia, Sarawak, Gunung Mulu | MT667277 | BOLD:AEE6243 |
Okalia necopinata JK204 | Malaysia, Sarawak, Gunung Mulu | MT667278 | BOLD:AEE6243 |
Okalia necopinata JK202 | Malaysia, Sarawak, Gunung Mulu | MT667279 | BOLD:AEE6243 |
Okalia globosa FZ2651 | Malaysia, Pahang | – | – |
Okalia globosa FZ0001 | Malaysia, Pahang | – | – |
Outgroup | |||
Graphelmis anulata FZ510 | Malaysia, Pahang | MK505424 | BOLD:ADC0259 |
Graphelmis obesa FZ544 | Malaysia, Sabah | MK505408 | BOLD:ADB9823 |
Graphelmis monticola FZ530 | Malaysia, Kelantan | MK505416 | BOLD:ADB9822 |
Altogether, nine sequences of O. necopinata were obtained and used together with two provided sequences of O. globosa (Table
Pairwise genetic distances (p-distance) between two Okalia species and the genus Graphelmis (outgroup).
O. necopinata JK097 | O. necopinata JK001 | O. necopinata JK201 | O. necopinata JK203 | O. necopinata JK205 | O. necopinata JK207 | O. necopinata JK206 | O. necopinata JK204 | O. necopinata JK202 | O. globosa FZ2651 | O. globosa FZ0001 | G. anulata FZ510 | G. obesa FZ544 | G. monticola FZ530 | |
O. necopinata JK097 | – | |||||||||||||
O. necopinata JK001 | 0.000 | |||||||||||||
O. necopinata JK201 | 0.000 | 0.000 | ||||||||||||
O. necopinata JK203 | 0.000 | 0.000 | 0.000 | |||||||||||
O. necopinata JK205 | 0.000 | 0.000 | 0.000 | 0.000 | ||||||||||
O. necopinata JK207 | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 | |||||||||
O. necopinata JK206 | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 | ||||||||
O. necopinata JK204 | 0.003 | 0.003 | 0.003 | 0.003 | 0.003 | 0.003 | 0.003 | |||||||
O. necopinata JK202 | 0.002 | 0.002 | 0.002 | 0.002 | 0.002 | 0.002 | 0.002 | 0.005 | ||||||
O. globosa FZ2651 | 0.024 | 0.024 | 0.024 | 0.024 | 0.024 | 0.024 | 0.024 | 0.028 | 0.023 | |||||
O. globosa FZ0001 | 0.028 | 0.028 | 0.028 | 0.028 | 0.028 | 0.028 | 0.028 | 0.031 | 0.026 | 0.003 | ||||
G. anulata FZ510 | 0.178 | 0.178 | 0.178 | 0.178 | 0.178 | 0.178 | 0.178 | 0.178 | 0.178 | 0.182 | 0.186 | |||
G. obesa FZ544 | 0.166 | 0.166 | 0.166 | 0.166 | 0.166 | 0.166 | 0.166 | 0.166 | 0.164 | 0.164 | 0.168 | 0.141 | ||
G. monticola FZ530 | 0.203 | 0.203 | 0.203 | 0.203 | 0.203 | 0.203 | 0.203 | 0.203 | 0.201 | 0.194 | 0.198 | 0.161 | 0.141 | – |
Length: 1.44–1.63 mm, width: 0.78–0.88 mm. Body widely obovate and strongly convex dorsally. Surface scarcely finely punctate, smooth; dorsal plastron on head, anterolateral portion of pronotum, and elytra between lateral margin and fifth interval. Pronotal median groove absent, sublateral carinae very fine, indistinct; femora moderately expanded; fifth elytral interval granulate on posterior half, sixth near apex, seventh entirely; elytral striae obsolete; elytral apices obliquely truncate; lateral sides of pronotum and elytra serrate. Penis apically arrowhead-shaped (in ventral/dorsal view). Ovipositor: coxite long and narrow; posterolateral angle strongly produced laterad, acute. Female internal genital tract with bursa copulatrix enlarged, saccular, as long as ovipositor, with a pair of mesal longitudinal sclerites, a pair of admedian densely denticulate sclerites, and with numerous short spinules, especially laterally; spermatheca with two branches.
The new species differs from Okalia globosa in the larger size, longer elytral declivity, and especially in the granulation of the fifth elytral interval being confined to the posterior half. Furthermore, the elytral and pronotal punctation is less distinct than in O. globosa. The arrowhead-shaped apex of the aedeagus is more elongate, and the apex of the coxite of the ovipositor is more strongly produced laterad and more acute.
Furthermore, the single available female from Sabah differs in the more extensive granulation of the fifth elytral interval, and the irregular microscopic wrinkles of the elytral intervals. This winged female has also a narrower and longer pronotum with lateral sides subparallel posteriorly, and the sublateral pronotal carinae are more prominent than in the new species.
The epithet, a Latin adjective (necopinata = unexpected, unforeseen), refers to the unexpected discovery of this species in a small, very slowly flowing stream, a somewhat atypical habitat for riffle beetles.
Female genitalia A Okalia necopinata sp. nov., ovipositor with bursa copulatrix and sternite VIII, paratype, ventral aspect B O. globosa Kodada & Čiampor, ovipositor with bursa copulatrix, paratype, ventral aspect C same, coxite and gonostylus, enlarged D O. globosa, spermatheca E O. necopinata, spermatheca F same, coxite and gonostylus, enlarged. Scale bar: 0.1 mm.
Very shallow, slowly flowing, meandering stream (Fig.
Holotype
♂ (CFDS): “Malaysia, Sarawak, Marudi distr., Gunung Mulu NP, 12.10.2018, (40) 4°02'59.5"N, 114°49'24.3"E, 70 m a.s.l., small stream in primary forest, Kodada & Selnekovič lgt.”. Paratypes including sequenced voucher specimens (CFDS, CKB,
Habitus (Fig.
Head. Partly retractable, retracted portion reticulated, without plastron structures; head width 0.31 mm; interocular distance 1.4× as long as longitudinal diameter of eye. Labrum wider than long, anterior margin with row of shorter trichoid setae ventrally, anterolateral portion with row of longer setae, posterior portion microreticulate. Clypeus about as long as labrum, wider than long; frontoclypeal suture distinct, arcuate; surface finely punctate, punctures setigerous, setae adpressed. Frons with setigerous micropunctures and scattered pointed granules; granules half as wide as a facete diameter, separated by distances of about 1.5–3.0× a facete diameter. Eyes small, feebly protuberant in dorsal view, ellipsoidal in lateral view, longer than wide, with about 50 facets (Fig.
Thorax. Pronotum slightly wider than long, widest near posterior fourth, PW: 0.54 mm, PL: 0.46 mm; disc strongly convex, sparsely, and finely punctate; punctures with moderately long semi-erect setae, distinctly smaller than facets, and separated by distances 1.5–3.0× of a facete diameter. Sublateral carinae indistinct, present on posterior fifth of pronotum; median groove absent; prebasal pits shallow; anterior margin translucent, moderately arcuate; anterior angles acute and strongly protruding; posterior angles with fine wrinkles; lateral margin serrate, more strongly along anterior than along posterior half. Plastron area nearly triangular, on each side of midline, widest anteriorly, reaching nearly midlength. Hypomeron broadest near middle, separated by a gap from prosternum anteriorly, postcoxal projection absent. Prosternum in front of coxae about as long as prosternal process, feebly deflected anteriad; prosternal process subtriangular, narrowed posteriad, with apex feebly rounded, nearly truncate, sides weakly and widely raised. Procoxae subglobular, separated near middle by distance of about 0.5× of head width (Fig.
Abdomen. Ventrites strongly sclerotized, moderately convex, separated by sutures; lateral margins of ventrites 1–2 evenly arched, in ventrites 3–4 projecting laterad (Fig.
Female genitalia. Ovipositor (Fig.
Females are on average slightly longer and broader than males. No other prominent secondary sexual characters were found.
The examined specimens vary moderately in punctation of pronotum and elytra as well as in size: BL ♂♂: 1.44–1.46 mm, ♀♀: 1.52–1.63 mm; EW ♂♂: 0.78–0.80 mm, ♀♀: 0.82–0.86 mm; PW ♂♂: 0.52–0.53 mm, ♀♀: 0.53–057 mm, PL ♂♂: 0.48–0.49 mm, ♀♀: 0.47–0.50 mm; EL ♂♂: 0.97–0.99 mm, ♀♀: 1.05–1.11 mm.
The species is so far known only from the type locality in Sarawak.
Borneo is an island with very high biodiversity; however, in the last 40 years, human activities have significantly impacted local biota (
We found all genera of Elmidae recorded from Borneo, though deforestation, climate change, and environmental pollution are very adverse factors seriously affecting insects on the island. We collected many species in streams flowing through secondary forests covering most of Sarawak, although in rather a low abundance. The remaining primary forests are relatively small and fragmented. Still, in their streams, we have confirmed a very high diversity and population density of Elmidae and Dryopidae (e.g.,
Surprisingly, in the numerous lotic habitats examined, we found Okalia in only one calcareous stream. We do not know whether this is due to extinction or due to very specific habitat requirements. The wingless populations are likely much more sensitive to environmental changes and appear to become extinct faster. We assume that the species only survives in primary rainforests and may also occur in nearby Brunei, like Ancyronyx pulcherrimus.
1 | Elytral interval 5 with densely spaced granules along posterior half (Figs |
O. necopinata sp. nov. |
– | Elytral interval 5 with densely spaced granules from anterior 0.1 to apex (Fig. |
O. globosa Kodada & Čiampor |
We wish to thank Engkamat Anak Lading and Afiza Nur Binti Omar (Forest Department Sarawak, Kuching) for the help in arranging the “Permission to conduct research on biological resources” (permit no. (93) JHS/NCCD/600-7/2/107 and park permit no. WL49/2018), as well as for their help in arranging other necessary administration processes. Bian Rumei (Office Manager) and Ellen McArthur (Research Coordinator) from Gunung Mulu Park (Sarawak) provided D. Selnekovič and J. Kodada with important information on the watercourses in Gunung Mulu National Park. Thanks are also due to Miroslav Záhoran (Comenius University in Bratislava, Bratislava, Slovakia) for taking the SEM micrographs. Fedor Čiampor and Zuzana Čiamporová-Zaťovičová (Zoology Laboratory, Plant Science and Biodiversity Centre, Slovak Academy of Sciences) provided us with barcoding COI sequences of Okalia globosa. Peter Boyce (Munich) is thanked for the identification of Phymatarum borneense. This study was supported by the Slovak Research and Development Agency under contract no. APVV-19-0076 and the Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic and Slovak Academy of Sciences (grant number VEGA 1/0515/19).