Grouvellinus luciaensis Freitag, Molls and Bouma, 2019

Freitag, Hendrik, Molls, Christian, Bouma, Aglaia M., Garces, Jhoana M., Rossato, Marzia, Cosentino, Emanuela & Delledonne, Massimo, 2019, Additional new species of Grouvellinus Champion 1923 (Insectaı Coleopteraı Elmidae) discovered by citizen scientists and DNA barcoded in the field applying a novel MinIONbased workflow, Journal of Natural History 53 (41), pp. 2593-2620 : 2608-2612

Grouvellinus luciaensis Freitag, Molls and Bouma , sp. nov.

( Figures 6 , 14 (a – d), 15(a – c))

Type locality. Malaysia, Sabah (on Borneo Island), Tawau Hills Park, Lucia River, 4° 28 ʹ 34 ʹʹ N, 117°55 ʹ 38 ʹʹ E, 750 m a.s.l. ( Figure 1 (f)).

Type material. Holotype 3 (SP): ‘ MALAYSIA: Sabah: Lucia River; rock surface, run; primary forest; ca. 4°28 ʹ 34 ʹʹ N, 117°55 ʹ 38 ʹʹ E, ca. 750 m a.s.l., leg. Taxon Expedition participants 10. March .2018 (6g)M ’, terminal parts of abdomen incl. aedeagus glued separately . Paratypes: 3♀ (SP) same data as holotype; 13 [H12], 2♀ (SP) ‘ MALAYSIA: Sabah: Lucia River; submerged wood, run; primary forest; ca. 4°28 ʹ 34 ʹʹ N, 117°55 ʹ 38 ʹʹ E, ca. 750 m a.s.l., leg. Taxon Expedition participants 10. March .2018 (6f)M ’ ; 3 1♀ [H22] (SP) ‘ MALAYSIA: Sabah: Lucia River; submerged root packs, run; primary forest; ca. 4°28 ʹ 34 ʹʹ N, 117° 55 ʹ 38 ʹʹ E, ca. 750 m a.s.l., leg. Taxon Expedition participants 10. March .2018 (6h)M ’.

Etymology

The species is named in reference to its type locality, Mt. Lucia and Lucia River originating there.

Description

Body elongate obovate, males 1.91 – 1.96 mm, females 1.97 – 2.04 mm long (CL); males 0.89 – 0.91 mm, females ca. 0.96 mm wide (EW), ca. 2.1 times as long as wide (CL/EW).

Dorsal colouration ( Figure 6 ) almost entirely dark brown to black; legs paler, at least distal half of femora and claws golden brown; maxillary and labial palps dark golden brown; pubescence shiny yellowish, rather inconspicuous. Ventral side ( Figure 14 (b – d)) dark brown.

Head ( Figure 14 (a)) 0.39 – 0.43 mm wide (HW); ID 0.19 – 0.24 mm; disc of frons, clypeus, and anterior and lateral areas of labrum sparsely pubescent; clypeus with two pairs of conspicuous sublateroanterior setae and entire frontal and lateral margins of labrum densely pubescent; punctures small; intervals glabrous; except for rugulouse frontal portion bordering eyes. Frontoclypeal suture straight, distinct. Eyes moderately large (eye diameter smaller than ID), slightly protruding. Antennae genus-typical.

Pronotum ( Figure 14 (a)) in males: 0.52 – 0.54 mm, in females: 0.53 – 0.57 mm long (PL); in males: 0.65 – 0.67 mm, in females: 0.66 – 0.72 mm wide (PW), wider than long (PL/PW), widest posterior 0 – 0.3, distinctly narrower than elytra, anteriorly attenuate; anterior margin slightly convex; pronotal disc moderately vaulted; entire pronotum moderately sparsely punctate; punctures small and shallowly impressed; median carina absent; with a pair of small and moderately deep posterior-median pits (anterior of the scutellum); sublateral carinae distinct and short; oblique impression moderately deep, narrow and glabrous, extending approx. anterior 0.35 – 0.65; laterobasal impression shallow, rugose; setae moderately short; interstices glabrous and flat. Hypomeron densely punctate, punctures large. Prosternum ( Figure 14 (b)) short; lateral portions with pubescence (plastron); median portion including process medially broadly impressed, slightly rugulose; prosternal process trapezoidal, slightly longer than wide, medially impressed.

Scutellum ( Figure 14 (a)) subtriangular, flat, glabrous. Elytra ( Figure 6 ) elongate, subparallel anterior 0.15 – 0.60, moderately convex dorsally, in males: 1.41 – 1.44 mm, in females: 1.44 – 1.48 mm long (EL), 1.5 – 1.6 times as long as wide (EL/EW), widest in anterior half; apices narrow, distinctly separately rounded; with eight longitudinal, distinctly impressed rows of punctures (striae); stria 8 reaching only up to 0.4 posterior; punctures somewhat regularly arranged, distinctly larger (diameter larger than interstices) and very deeply impressed in anterior and lateral portions, increasingly shallower and smaller apicad; interstices glabrous to finely rugulouse; median elytral portion, especially along interval 1 with additional very small setiferous secondary punctures; pubescence inconspicuous, consisting of very small adpressed setae and moderately large erected setae; interval 8 evenly carinate, but not serrate; interval 7 very slightly carinate; interval 5 (and intervals 2 – 4 in lesser extent) broadly elevated in subanterior portion; lateral elytral margin carinate with fine serration.

Mesoventrite ( Figure 14 (c)) with two pairs of shallow grooves behind procoxae and medially, respectively. Metaventrite ( Figure 14 (d)) moderately densely punctate, less densely at disc; longitudinal impression along entire median suture; lateral portions rather flat with inconspicuous plastron and a row of large punctures behind mesocoxae.

Ventrite 1 ( Figure 14 (d)) with pair of longitudinal carinae bordering disc; disc glabrous, sparsely punctate; lateral portions inconspicously pubescent (plastron); broad lateral portions of ventrites 1 – 4 and almost entire ventrite 5 ( Figure 14 (d)) densely covered with rather inconspicuous micro-plastron; ventrite 5 densely covered with setiferous tubercles and with apical fringe of moderately long setae.

Legs ( Figure 6 ) approximately as long as body; hindleg longest; tibia longer than tarsus and femur in all legs; proximal portion of mesofemur with loose fringe of moderately long trichoid setae at anterior-dorsal ridge (in both sexes); distal area of all tibiae with more or less densely covered with short trichoid setae; hind tibia additionally with loose longitudinal fringe of robust spine-like setae; coxae, trochanter, and particularly inner and posterior faces of femora and tibiae covered with conspicuous plastron setae. Legs not conspicuously varying between sexes.

Aedeagus ( Figure 15 (a,b)) ca. 635 μm long, ca. 190 μm wide. Base reaching basal 0.38 of total aedeagus length. Median lobe ca. four times as long as wide, moderately overreaching parameres, abruptly tapering in apical third towards the slender conical, rounded apex. Ventral sac apically inflated overreaching median lobe and parameres, internally densely stippled and with dense submedian fringes of moderately long, thin spines; apically the spines get longer and reach the apical opening. Parameres apically moderately conical (in both, ventral and lateral view), usually with more than 50 trichoid setae in apical two-third, most of them at the outer ventral face; most apical two setae longest and inserted at the apex. Male sternite IX as in previous new species.

Ovipositor ( Figure 15 (c)) total length ca. 790 μm; stylus ca. 40 μm long, moderately bent outwards with three short sensilla; coxite ca. 375 μm long with scattered extremely short, acute setae and four hook-like bent sensilla, apically moderately broadened at outer margin, valvifer ca. 430 μm long, caudal portion slightly sclerotised and with very few scattered, extremely short, acute setae; fibula almost straight.

Sexual dimorphism

Females with separately rounded and slightly more pointed elytral apices.

Differential diagnosis

Grouvellinus luciaensis sp. nov. can be distinguished from all known Bornean Grouvellinus spp. by its moderately large size (CL) of 1.91 – 2.04 mm (vs. ≤ 1.9 mm, or ≥ 2.3 mm), somewhat straight conical elytral posterior portion, very deeply impressed elytral striae in anterior and lateral portions, and a non-serrate 8th elytral interval. Furthermore, it is recognisable by the slight and uniform reddish-brownish tinge of the body, comparably pale femora, the aedeagal median lobe that is abruptly tapering in apical third and the comparably broad parameres with more than 50 trichoid setae in apical two-third.

The species varies by about 11 – 17% genetic distance (654 bp CO1 barcode) from the Bornean congeners.

Distribution

This species is only known from the type locality, upper Lucia River, Tawau Hills Park, Sabah, Borneo Island ( Figure 18 ).

Figures

Figure 1. (a) Co-authors and assistants of the Taxon Expedition to Tawau Hills Park, Sabah, Malaysian Borneo, performing microhabitat-specific sampling; (b) Co-authors during beetle collection at a blacklight trap installed in the vicinity of the Tawau River; (c) The first author (second from the right) instructing Taxon Expedition participants on the identification of riffle beetles; (d) the transportable molecular field laboratory at the Tawau Park Station; (e) Type locality of Grouvellinus borneensis, sp. nov., G. cruxniger, sp. nov., G. nigerquadratus, sp. nov., and collection site of G. sp. 1; (f) Type locality of Grouvellinus luciaensis, sp. nov., and collection site of G. andrekuipersi, G. nigerquadratus, sp. nov. and G. sp. 2.

Figure 14. Grouvellinus luciaensis, sp. nov. (paratypes): (a) anteriodorsal aspect with pronotum; (b) anterioventral aspect with head and prosternum; (c) ventral aspect with prosternum and mesoventrite, (d) posterioventral aspect with metaventrite and ventrites 1–5.

Figure 15. Grouvellinus luciaensis, sp. nov. (paratypes): (a) aedeagus, lateral; (b) aedeagus, ventral; (c) ovipositor (half), ventral. Scale bar = 0.1 mm.

Figure 18. Map of Sabah and Brunei (Borneo) with collecting site of Grouvellinus species with new species record in red fonts.

Figures 6–9. Habitus of the Grouvellinus species collected from the Tawan Hills Park. 6: G. luciaensis, sp. nov. (paratype male from Lucia River); 7: G. borneensis, sp. nov. (paratype male from Tawau River environment); 8: G. sp.1 (female from Tawau River environment); 9: G. sp.2 (female from Lucia River). Scale: 1 mm.