Gibbidessus davidi, Hendrich & Watts & Balke, 2020

Hendrich, Lars, Watts, Chris H. S. & Balke, Michael, 2020, The " minute diving beetles " of southern Australia - taxonomic revision of Gibbidessus Watts, 1978, with description of six new species (Coleoptera, Dytiscidae, Bidessini), ZooKeys 975, pp. 11-49 : 11

publication ID	https://dx.doi.org/10.3897/zookeys.975.55456
publication LSID	lsid:zoobank.org:pub:785EDF22-5A32-4217-8C9B-6433E0AD199F
persistent identifier	https://treatment.plazi.org/id/4D235E7C-F517-4C1D-A3C7-0C87BDA34515
taxon LSID	lsid:zoobank.org:act:4D235E7C-F517-4C1D-A3C7-0C87BDA34515
treatment provided by	ZooKeys by Pensoft
scientific name	Gibbidessus davidi
status	sp. nov.

Treatment

Gibbidessus davidi sp. nov. Figs 3 View Figures 1–4 , 4 View Figures 1–4 , 12 View Figure 12 , 16 View Figures 16, 17 , 23 View Figures 22, 23 , 27 View Figure 27 , 28 View Figure 28

Type locality.

Western Australia, Perth, suburb Success, Beeliar Regional Park, shallow peaty puddle [32°8'4S, 115°50'22E].

Type material.

Holotype, male: "Australia, WA, Perth, Success, Beeliar RP, shallow peaty puddle 32°8'4.97"S, 115°50'22.78"E 21.-31.10.2015 L. Hendrich (WA 1/15)", "Holotype Gibbidessus davidi Hendrich, Watts & Balke des. 2020" (WAM) [red printed label]. Paratypes (370 exs.). 354 specimens with same data as holotype (ANIC, CGC, CLH, SAMA, WAM, ZSM); 4 exs, "Australia: SW WA, D´Entrecasteaux NP, 11 km S, Northcliffe, 77m, 4.I.2007, 34.44.048S, 116.05.354E [34°44'0S, 116°5'13E], L. & E. Hendrich (WA 162)" (ZSM); 10 exs., "Australia, WA, Albany Hwy, Muir Lakes Nature Reserve, SW part of Byenup Lagoon, 4.& 5.1.2000, 34°30'4S, 116°44'19E, Hendrich leg. (loc. WA 11/157)" (CLH, ZSM); 1 ex., "Australia, WA, Barlee Brook Dickson Road (A) [34°12'17S, 115°46'18E], DON03, 21/10/2005, South West Forest Monitoring" (DPAW); 1 ex., "Australia, WA, Fish Creek (A) [34°37'29S, 116°26'11E], SHA22, 17/10/2010, South West Forest Monitoring" (DPAW); 4 exs., "Australia, WA, RVDLE03 Riverdale Wetland [32°59'23S, 115°47'23E], 23/09/2008, South West Catchment Council Mon." (DPAW). All paratypes with red printed paratype labels.

Diagnosis.

Small species which externally is characterised by a wide rounded body, shiny non-microreticulate dorsal surface, vague testaceous markings on elytra, and without habitus disruption between pronotum and elytron. Dorsoventrally rather domed. Cervical line present (Fig. 3 View Figures 1–4 ).

Measurements.

Holotype: TL = 1.45 mm, TL-H = 1.35 mm, MW = 0.83 mm. Paratypes: TL = 1.35-1.5 mm, TL-H = 1.15-1.4 mm, MW = 0.8-0.9 mm.

Head: Ferruginous, around eyes almost black. Cervical line present (Fig. 12A View Figure 12 ). Strongly and coarsely punctate, rather shiny, microreticulation present. Punctures weak anteriorly and strongly posteriorly between eyes. Antennae relatively short, stout. Antennomeres 1-8 ferruginous, 9-11 darkened anteriorly.

Pronotum: Ferruginous, anterior and posterior margins darker. Disc of pronotum somewhat darkened, broadest at posterior corners. Punctation of pronotum very weak, almost evenly distributed, shiny and microsculpture absent. Sides of pronotum margined and almost evenly rounded. Angle between pronotum and elytra less pronounced, basal pronotal plicae present. Striae moderately defined, almost 1/2 length of pronotum, strongly incurved.

Elytra: Dark brown with vague basolateral area ferruginous (Fig. 3 View Figures 1–4 ). Coarsely and densely punctate, shiny, microsculpture absent. Striae deeply impressed, straight but shorter than basal pronotal striae.

Ventral side: Ferruginous. Prothorax and abdomen paler than other parts. Metacoxae and metaventrite covered with larger punctures, surface shiny, without microreticulation. Abdominal ventrites with dense and finer punctures, shiny, microreticulation absent. Metacoxal lines almost straight, anteriorly not divergent. Epipleuron ferruginous, with few coarse punctures, shiny, lacking microsculpture. Legs ferruginous with meta-/mesotibia and meta-/mesotarsi set in black.

Male. Smaller and more elongate than female (Fig. 4 View Figures 1–4 ). Median lobe of aedeagus as in Fig. 16A, B View Figures 16, 17 . Shape of median lobe in lateral view, straight and fairly uniform, in ventral view broad, with a thorn on each side, and rounded at apex. Parameres bi-segmented and elongated with few setae at apex (Fig. 16C, D View Figures 16, 17 ).

Affinities.

This species is similar to G. atomus sp. nov. but readily separated by its larger size, the different colour pattern and the form of the median lobe and parameres (Figs 14 View Figures 14, 15 , 16 View Figures 16, 17 ). From G. pederzanii sp. nov. it can be distinguished by the less roundish body and the form of the median lobe and parameres (Figs 16 View Figures 16, 17 , 19 View Figures 18, 19 ).

Etymology.

The beetle is named after the son of the first author, David Hendrich. The specific epithet is a substantive in the genitive case.

Distribution.

South-western Australia. From Perth in the north to D´Entrecasteaux National Park in the south (Fig. 23 View Figures 22, 23 ).

Habitat.

In the Northcliffe area most specimens were obtained from an exposed, shallow and small roundish puddle, without any vegetation, except some algae. The other specimens were collected in a half-shaded pool in a Melaleuca blackwater swamp, with few clumps of Juncus spp. and extensive beds of macrophytes; depth up to 20 cm; bottom consisted of sedge-filled peat (pH 5.5), twigs and rotten leaves (Figs 27 View Figure 27 , 28 View Figure 28 ). The whole area south of Northcliffe is seasonally flooded with some permanent central water bodies in summer. In the D´Entrecasteaux NP the species is syntopic with G. atomus sp. nov., and around Perth in the Beeliar Regional Park with G. rottnestensis sp. nov. At the Riverdale Wetland Reserve G. davidi sp. nov. was syntopic with G. atomus sp. nov. and G. rottnestensis sp. nov.