Ochthebius (Aulacochthebius) multilineatus, Perkins, 2023

Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), Zootaxa 5228 (5), pp. 501-546 : 537-544

O. (Aulacochthebius) multilineatus , new species

Figs. 2 , 4 , 20 , 31

Type Material. Holotype (male): “ Madagascar (55), 31.08.2001 / Ifotaka (Tulear), Morafena, left affl. / Riv. Mandrare upstr. vill., stagnant / pools near mouth 65 m asl. / Gerecke & Goldschmidt coll.” ( NMW) . Paratype (1 female, same data, NMW) .

Differential diagnosis. Differentiated from other similar members of the O. (A.) tenuipunctus Group by the combination of the elytral sculpture, each serial row with a wide band of very fine microreticulation (or internal structure appearing to be microreticulation – see notes) which are separated by extremely weakly raised smooth and shining longitudinal lines; and by the aedeagal morphology ( Fig. 20 ).

Description. Size: holotype (length/width, mm): body 1.40/0.67 (length to elytral apices); head width 0.38; pronotum length 0.28, width at base 0.27, width at hyaline border 0.61, width of lateral sclerotized lobes 0.47 at anterior, 0.24 at posterior; elytra 0.81/0.67. Habitus as illustrated ( Fig. 20 ). Body longitudinally and transversely very convex. Dorsum dark brown, legs lighter, except hyaline borders of prothorax translucent to light yellowish with debris. Eyes with moderately coarse, convex facets. Dorsum of head and non-hyaline part of pronotum very faintly, effacedly microreticulate; setae very indistinct, very sparse and very short, except dense on labrum and at lateral borders of clypeus. Frons with deep impressions, borders of impressions rounded, smooth. Labrum anterior margin arcuate.

Pronotal reliefs smooth, with very sparse and very short setae; anterior and posterior transverse impressions deep, anterior contiguous with shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression short, shallow, extending from anterior transverse impression to ca. midlength. Pronotum anterior margin bisinuate. Pronotum lateral hyaline borders very wide, extended from posterior to anterior angles, outer margin markedly arcuate; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior hyaline border very narrow, posterior hyaline border absent.

Elytra very slightly wider than hyaline part of pronotum, posteriorly acuminate, sides markedly arcuate; each elytron with 10 serial rows of very short, widely spaced setae; each row with wide band of very fine microreticulation which are separated by extremely weakly raised smooth and shining longitudinal lines; lateral margin with very long setae at and slightly behind humeral angle, otherwise margin with very dense, very short setae that extend outward from wide lateral explanate margin.

Venter ( Fig. 11 ): Mentum with sparse, moderately large setigerous punctures. Prosternum without midlongitudinal carina. Metaventrite tabella large, oval to suboval, very slightly angulate anteriorly, width and length ca. equal, slightly convex; first four ventrites bearing rather long hydrofuge pubescence; remaining ventrites glabrous, shining, with sparse setae.

Etymology. Named in reference to the multiple alternating lines of the elytra (see Notes).

Distribution. Currently known only from the type locality ( Fig. 31 ).

Notes. When examined with standard stereoscope lighting (no diffuser), the elytra of this species have distinct longitudinal lines consisting of what appears to be extremely fine microreticulation, separated by very narrow very slightly raised shining lines (see image of elytron, inset on Fig. 20 ). However, when a diffuser is used for the lighting (which is the standard method used herein for imaging), the microreticulation does not appear. What appears to be microreticulation might be internal structure causing reflections; scanning electron micrographs are needed to confirm this view.

Figures

FIGURE 2. Dorsal habitus of species in O. (A.) tenuipunctus Group.

FIGURE 4. Venter and aedeagi (ventral view, flagellum deleted) of species in O. (A.) continentalis Group and O. (A.) tenuipunctus Group. Not to same scale.

FIGURE 11. O. (A.) flagellisimus n. sp., holotype habitus and aedeagus.

FIGURE 20. O. (A.) multilineatus n. sp., holotype habitus and aedeagus (inset: image taken without light diffuser; see text).

FIGURES 31–32. Geographical distributions. 31. O. (A.) plicicollis Fairmaire. 32. O. (A.) perlaevis (Perkins).