Ancyronyx procerus Jaech , 1994

Kodada, Jan, Jaech, Manfred A., Freitag, Hendrik, Ciamporova-Zatovicova, Zuzana, Goffova, Katarina, Selnekovic, David & Jr, Fedor Ciampor, 2020, Ancyronyx clisteri, a new spider riffle beetle species from Borneo, redescription of A. sarawacensis Jaech including a description of the larva and new distribution data for A. procerus Jaech using DNA barcodes (Coleoptera, Elmidae), ZooKeys 912, pp. 25-64 : 25

Ancyronyx procerus Jaech, 1994

Type locality.

Tributary of the Tutoh River, near Long Iman, Mulu National Park, northern Sarawak, Borneo, East Malaysia.

Material examined.

Holotype ♂ (NMW): "Malaysia, Sarawak, Mulu NP, Long Iman 4.3.1993 leg. M. Jäch (20)". Paratypes: 5 exs with same data as holotype (NMW), 2 exs (CKB): "Malaysia - Sarawak ca 40 km E Kapit III. 1994 leg. J. Kodada \ Rumah ugap Ng marating Kapit Sut".

Additional material

(CCB, CFDS, CKB, NMW). SARAWAK: 1 ♀ [37, MK505417], 1 ♀ [FZ1639, MK505411], 2 exs: "Malaysia, Sarawak, Kuching distr., Kampong Jantar env., 10.7.2018, (29) 1.65911N, 109.70829E, 67 m a.s.l., J. Kodada & D. Selnekovič lgt."; 1 ♀ [11, MK505423], 1 ♂ [FZ1644, MK505410], 2 exs: "Malaysia, Sarawak, Kuching distr., Bayur riv. near bridge of jalan Jambur - Bayur, 20.10.2018, 1°14'43.2"N, 110°17'34.8"E, ca 50 m a.s.l., J. Kodada & D. Selnekovič lgt."; 3 exs: "Malaysia, Sarawak, Miri distr., Ramudu env., 5.03.2019, (No. 51), Ramudu riv., 3°32'14.390"N, 115°30'22.456"E, ca 900 m a.s.l., J. Kodada & D. Selnekovič lgt."; 4 exs: "Malaysia, Sarawak, Miri distr., Ramudu env., 6.03.2019, (No. 52), Pa‘Masia riv., ca 3°31'57.736"N, 115°30'39.624"E, ca 950 m a.s.l., J. Kodada & D. Selnekovič lgt."; 10 exs: "Malaysia, Sarawak, Miri distr., Dapur riv. near Pa’Umor, 8.03.2019, (No. 54), 3°44'3.49"S, 115°30'56.24"E ca 1070 m a.s.l., J. Kodada & D. Selnekovič lgt.". SABAH: 1 ♂: "Malaysia, Sabah, ca 25 km Sapulut, Sabalangang river, 21.V.2001"; 1 ♂, 3 ♀♀, 4 exs: "Malaysia, Sabah, (Borneo), Kuamut river env. near Kampung Pisang Pisang, 3.-4. VI. 1996, 14a: shaded stream in primary forest with submerged wood"; 1 ♂, 1 ex.: "Malaysia, Sabah, Kampung Pisang Pisang env., tributary of Kuamut River, 29.6.1998, J. Kodada & F. Čiampor Lgt."; 1 ex. [FZ1660, MK505403], 1 ♂: "Malaysia, Sabah, Interior Division (Nabawan), Batu Punggul env., 23.5.2001, Čiampor lgt.". West Malaysia: PAHANG: 1 ex. [FZ1659, MK505405], 8 ♂♂, 3 ♀♀: "Malaysia, Malaysia, Pahang, Kenong Rimba Park, Kesong River, 5.6.2001, J. Kodada & F. Čiampor”. TERENGGANU: 4 exs [FZ1623, MK505419; FZ1624, MK505413, FZ1625, MK505402; FZ1626, MK505412]: "Malaysia, Terengganu, Kg. Pancur Merah env., stream ca 7m wide, 5°33'28.86"N, 102°40'47.70"E, 2.8.2016, ca 30 m a.s.l.".

Variability.

Ancyronyx procerus represents the largest species of the genus (TL 2.4-2.8 mm) with two, more or less distinct color forms. The form with lighter (less black) elytra and sometimes smaller to obsolete femoral spot correspond in habitus to the type specimens from Long Iman, Sarawak (see Jäch 1994: fig. 28). These lighter specimens were found, e.g., in all Sarawak lowland localities and in Sabah, in the Sabalangang River and in the tributary of the Kuamut River. The darker form with extensive black elytra and darker femoral spot were found in Sarawak in the rivers of the Kelabit Highlands, Sabah and in localities from West Malaysia. These color forms do not represent separate taxa, neither according to their genetic differentiation in COI mtDNA sequences, nor according to the fine differences in their genital morphology.

Habitat.

All Ancyronyx procerus were sampled from submerged wood and seem to prefer larger pieces of fresh wood with bark; so far none of the specimens were found on submerged exposed roots of living trees or bamboo like adults of A. sarawacensis or A. acaroides (Kodada and Selnekovič pers. obs.). Adults have also not been collected in light traps yet. The larva was described after two specimens, one from type locality and one from Busuanga Island (Philippines); association with adults was corroborated by COI mtDNA sequences ( Freitag and Balke 2011).

Specimens were usually found in smaller shallow meandering rivers with low vertical gradient, or - less frequently - in lowlands streams/creeks with a rather slower current, mostly with gravel or sandy substrate (e.g., Kesong River, rivers near Kampung Jalan and Kampung Bayur, Sabalangan River). In mountainous habitats the species is newly recorded from rivers in the Kelabit Higlands: Dapur, Ramudu and Pa’Masia; all these localities are within altitudes of 900-1070 m a.s.l. The largest of these rivers is the Dapur River; at the collecting place near Pa’Umor it is about 10-15 m wide, deep, reddish colored, meandering, with sandy bottom, and contains lot of submerged logs; the water level is strongly fluctuating annually. The partly shaded forest rivers Pa’Ramudu and Pa’Masia are 7-10 m wide, shallow, slowly flowing and meandering, with stones, some cobbles and gravel, and with some submerged wood and a lot of exposed bamboo roots.

Examination of flooded wood in larger rivers at lowland reaches of Sarawak (e.g., the Sarawak River at Kuching, the Rajang River at Kapit, Batang Kayan River near Lundu) did not yield any Ancyronyx specimens.

Distribution.

Ancyronyx procerus was described from a tributary of the Tutoh River near Long Iman in Mulu National Park (Sarawak). The type series contains 12 specimens from the type locality and two specimens from the river Sut near Kapit (Sarawak). Recent collecting activities in northern Borneo showed that A. procerus is less abundant than A. sarawacensis or A. acaroides .

Ancyronyx procerus was recorded from Brunei, Malaysia (Pahang, Sarawak), the Philippines (Busuanga) and Vietnam ( Jäch et al. 2016). The distributional data from Sabah and Terengganu represent first records from these states.