Liocanthydrus octoguttatus ( Zimmermann, 1921 )

Baca, Stephen M., Gustafson, Grey T., Toledo, Mario & Miller, Kelly B., 2014, Revision of the Neotropical burrowing water beetle genus Liocanthydrus Guignot (Coleoptera: Noteridae: Noterinae: Noterini) with the description of two new species, Zootaxa 3793 (2), pp. 231-246 : 244-245

Liocanthydrus octoguttatus ( Zimmermann, 1921)

Canthydrus octoguttatus Zimmermann (1921: 189) (orig. descr.); Blackwelder (1944: 73). Liocanthydrus octoguttatus (Zimmermann) ; Nilsson (2011: 28) (cat.).

Canthydrus (Liocanthydrus) octoguttatus (Zimmermann) ; Guignot (1957: 43); Nilsson (2005: 110) (cat.).

Type locality. Brazil, São Paulo State, São Paulo, Sierra da Cantareira.

Type material examined. Lectotype (male) (designated here): “Riedel” [printed] “ BRASIL /S. Paulo/ Umgebung v. S. Paulo/Sierra da Cantareira/ 19. Oct. 1900 ” [printed], “ Type ” [small round label, handwriting A. Zimmermann], “ Canthydrus octoguttatus ” [printed], “Samml. A. Zimmermann” [printed], plus an additional, unwritten, red label and our lectotype designation label: “ LECTOTYPE / Canthydrus octoguttatus / Zimmermann, 1921 /det. Baca, Gustafson, Toledo, Miller 2014” [red; printed]. ( ZSM). Paralectotype (female): “Riedel” [printed] “ BRASIL /S. Paulo/Umgebung v. S. Paulo/Sierra da Cantareira/ 19. Oct. 1900 ” [printed], “ Type ” [small round label, handwriting A. Zimmermann], “Samml. A. Zimmermann” [printed], “ Paratypus ” [red, unauthorized curatorial label; printed], plus our yellow paralectotype label: “ PARALECTOTYPE / Canthydrus octoguttatus / Zimmermann, 1921 /det. Baca, Gustafson, Toledo, Miller 2014” [yellow; printed] ( ZSM). Note: All label descriptions are included in brackets.

Diagnosis. Elytra maculate, distinguishable from other members of Liocanthydrus by the following combination of characters: a) small eye size relative to head capsule, HW/EW = 1.55 ( Fig. 9 ); b) elytral patterning as in Fig. 9 , with posterior bands oblique and nearly reduced to spots; anterior bands reduced to spots; c) aedeagus as in Figs 22 a–e; median lobe slightly sinuate in dorsal aspect ( Fig. 22 b), distally very elongate and subparallel with rounded apex in lateral aspect, not attenuate ( Figs 22 a, c); left lateral lobe narrowed distally ( Fig. 22 d); right lateral lobe triangular, distal angle acute, not projected ( Fig. 22 e).

Externally L. octoguttatus appears very similar to L. nanops and also, though less so, to Liocanthydrus clayae . Externally L. octoguttatus is distinguished from L. clayae by its small relative eye size and the more strongly obliquely oriented posterior elytral maculae that also extend anteriorly to the basal halves of the elytra. Liocanthydrus octoguttatus is distinguished from both L. octoguttatus and L. nanops by its distinct aedeagus, with a median lobe that is distally very elongate and subparallel in lateral aspect, not attenuate as in both L. clayae and L. nanops, Also , the right lateral lobe of the aedeagus is triangular with an acute distal angle, similar to L. clayae but not subtriangular with the distal angle strongly projected as in L. nanops .

Description. Measurements. TL = 3.05 mm, GW = 1.4 mm, TL/GW = 2.18, HW = 0.85 mm, EW = 0.55 mm, HW/EW = 1.55, PNWpost. = 1.35 mm, PNWant. = 0.85 mm, PNWpost./PNWant. = 1.59.

Coloration. Elytra maculate, with bands or spots; color of elytra dark reddish brown; color of head, pronotum and elytral maculae yellow; band pattern as in Fig. 9 , posterior elytral band strongly oblique and extending anterolaterally to basal halves of elytra, anterior bands reduced to spots and laterally oriented, with medial spots larger, more distinct than lateral spots; anteromedial portion of pronotal disc with distinct large dark maculation ( Fig. 9 ).

Body. Body forms as in Fig. 9 , oval, moderately narrow, attenuate posteriorly.

Abdomen. Aedeagus as in Figs 22 a–e; median lobe sinuate in dorsal aspect ( Fig. 22 b), distally elongate and subparallel in lateral aspect, apex rounded. ( Figs 22 a, c); left lateral lobe broad and rounded near base but narrowed distally, setal fringe expanded to small field apically and barely extending basad of distal third ( Fig. 22 d); right lateral lobe triangular, distal angle acute.( Fig. 22 e).

Biology. No collection data available.

Distribution. Known only from São Paulo, Brazil ( Fig. 23).

Variation. The variation exhibited by this species was difficult to assess due to the limited amount of material available for examination. As mentioned, the type of L. octoguttatus has a large, very dark maculation on the anteromedial region of the pronotum ( Fig. 9 ), much larger and darker than any of the other species of Liocanthydrus . However, the variation of this feature could not be assessed and may not be useful as a diagnostic character as similar though far less distinct markings were observed to vary within other species of Liocanthydrus .

Figures

FIGURES 3 – 9. Liocanthydrus species, dorsal habitus: 3) L. angustus; 4) L. uniformis; 5) L. bicolor; 6) L. armulatus sp. n.; 7) L. clayae; 8) L. nanops sp. n.; 9) L. octoguttatus (illustration). Scale bar = 1.0 mm.

FIGURES 16 – 22. Aedeagi of Liocanthydrus species. a) median lobe, right lateral aspect; b) median lobe, dorsal aspect; c) median lobe, left lateral aspect; d) left lateral lobe, right lateral aspect; e) right lateral lobe, left lateral aspect: 16) L. angustus; 17) L. uniformis; 18) L. bicolor; 19) L. armulatus sp. n.; 20) L. clayae; 21) L. nanops sp. n.; 22) L. octoguttatus. Scale bars = 0.2 mm. Notes: Terminology follows K. B. Miller & Nilsson (2003). Illustrations of lateral lobes depict medial (inner) surfaces.