Ancyronyx pulcherrimus Kodada, Jaech & Ciampor , 2014

Kodada, Jan, Jaech, Manfred A., Freitag, Hendrik, Ciamporova-Zatovicova, Zuzana, Goffova, Katarina, Selnekovic, David & Jr, Fedor Ciampor, 2020, Ancyronyx lianlabangorum sp. nov., a new spider riffle beetle from Sarawak, and new distribution records for A. pulcherrimus Kodada, Jaech & Ciampor based on DNA barcodes (Coleoptera, Elmidae), ZooKeys 1003, pp. 31-55 : 31

Ancyronyx pulcherrimus Kodada, Jaech & Ciampor, 2014

Type locality.

Ingei River, forest pool,, Belait District, Brunei.

Material examined.

Type material. Holotype ♂ (BM): "Brunei: Belait Distr. Sg. Ingei, forest pool near Base Camp, 14.VI.2010 leg. Mayyer Ling (34)". Paratypes (NMW, UB): 1 ♂ and 2 ♀♀, same label data as holotype.

Additional material

(CCB, CFDS, CKB, NMW, UBDM).

Lineage 1. Sarawak 9 ♂♂ [incl. JK100, JK213, JK214, JK215], 15 ♀♀ [incl. JK101, JK102, JK208, FZ1632]: "Malaysia, Sarawak, Marudi distr., Gunung Mulu NP, 16.10.2018, (40) 04.0267°N, 114.8234°E, 55 m a.s.l., small stream in primary forest, Kodada & Selnekovič lgt.". Brunei 2 ♂♂, 1 ♀ [FR324]: "Brunei: Temburong; small Sungai Peradayan; rivulet, subm. wood; dist. primary forest; c. 25m a.s.l. c. 04.11.1997 leg. Mendoza (6f)".

Lineages 2 and 3. Sarawak 5 ♂♂ [incl. JK105, JK106], 1 ♀ [JK12]: "Malaysia, Sarawak, Kuching distr., Bayur riv. near Kampung Bayur, 20.10.2018, 1°14'42.3"N, 110°17'35.3"E 40 m a.s.l., J. Kodada & D. Selnekovič lgt."; 2 ♂♂ [JK197, JK199], 4 ♀♀ [incl. JK193, JK195]: same locality and collectors, but 22.02.2019, (No.43); 1 ♂ [FR344]: "Malaysia: Sarawak, Kg. Bayur 35km SSE Kuching, small hill river Bayur R.; run, subm. wood; second. veget./farmland; c. 50m a.s.l., c. 12.11.1993 leg. Mendoza (19f)".

Variability.

Ancyronyx pulcherrimus was represented by three barcode lineages, which are tentatively considered conspecific in the absence of further evidence. The specimens of the first lineage were collected in northern Sarawak and Brunei, while the specimens of the second and third lineages occur sympatrically in southwestern Sarawak. The first lineage is characterized by: (1) elytra predominantly black with a central yellowish, nearly X-shaped pattern and yellowish apices; (2) femora with black band between middle and proximal fourth; and (3) tibiae black on proximal three-quarters (compare Fig. 4 in Kodada et al. 2014). The type specimens are rather uniform in these characters, and all individuals recently collected in Gunung Mulu NP generally agree with them. However, there is some minor variation in the extent of the black coloration of the elytra, pronotum and legs (Fig. 4A, B ). The examination of the hind wings of six specimens of the Gunung Mulu population and three specimens from Temburong (Brunei) revealed only short wings not reaching the abdominal apex (Fig. 4B ). Macropterous or apterous forms were not detected, and the elytral shape of the remaining specimens suggests that they are flightless too.

The specimens of the second and third lineages differ from the type specimens in the predominantly yellowish elytra, which are provided with several black lateral and sutural spots of variable size. The pronotal spots are usually smaller, and the dark femoral bands are smaller, paler or obsolete (Fig. 4C, D ). The examination of their hind wings revealed one macropterous and five brachypterous specimens.

Lineages detected by the analysis of COI nucleotide sequences were not confirmed by PCA analyses of morphometric characters (Fig. 2 , Table 4 ) or corroborated by the genital morphology.

Habitat and syntopic taxa.

The stream inhabited by a large population of A. pulcherrimus was a small, slowly flowing, very shallow, and entirely shaded meandering creek in Gunung Mulu NP (55 m a.s.l.). It included large amounts of accumulated leaves, and the bottom substrate contained sand and gravel, as well as woody debris (Fig. 5D ). The specimens co-occurred with Ancyronyx sarawacensis and two new species of Elmidae ( Okalia Kodada & Čiampor and Leptelmis ).

The second population was found in a moderately wide (5-8 m) lowland river near Kampung Bayur (Kuching Division); the sampled stretch was shallow and meandering, with sandy/gravelly substrate containing submerged logs, woody debris, and leaves. All specimens were collected exclusively in reaches with stronger current from submerged logs together with Ancyronyx procerus , A. acaroides , and several other Elmidae ( Leptelmis sp. and Graphelmis spp. of the G. picta (Reitter) and G. marshalli Hinton species groups).

Distribution.

Ancyronyx pulcherrimus was so far known only from Brunei ( Jäch et al. 2016). The species is here recorded for the first time from Malaysia, where it was collected in Gunung Mulu NP (northern Sarawak) and in the Kuching Division (southwestern Sarawak).

Our recent collecting activities found A. pulcherrimus to be less abundant and less widely distributed than A. sarawacensis , A. procerus , or A. acaroides , probably also due to the low dispersal ability of flightless populations.

Figures

Figure 2. Results of the PCA analysis showing ordination of Ancyronyx lianlabangorum sp. nov. and A. pulcherrimus Kodada, Jaech & Ciampor specimens along the first two principal components A males B females. Clusters of A. pulcherrimus specimens on left side of plot (yellow lines), clusters of A. lianlabangorum sp. nov. on right side (green lines). Yellow circles: A. pulcherrimus specimens from Gunung Mulu NP, first lineage; blue circles: A. pulcherrimus from Bayur River, second lineage; brown circles: A. pulcherrimus from Bayur River, third lineage; black circles: A. pulcherrimus from Bayur River, specimens not barcoded, not assignable to the first or second lineage according to morphology; red circle: A. pulcherrimus from Brunei; green squares: A. lianlabangorum sp. nov. Genetic voucher IDs are included according to Table 1.

Figure 4. Ancyronyx pulcherrimus A male from Gunung Mulu NP, body length 1.82 mm B brachypterous male from Gunung Mulu NP, dorsal view (left elytron and apical segments of abdomen removed), body length 1.92 mm C male from Bayur River, dorsal view, body length 1.70 mm D male [JK 106] from Bayur River, dorsal view, body length 1.70 mm.

Figure 5. Habitats of Ancyronyx lianlabangorum sp. nov. (A-C) and A. pulcherrimus (D) A type locality, Pa' Ramudu River B Pa' Masia River C Pa' Kasi River D shaded shallow creek in primary forest, Gunung Mulu NP.