Orphilus niger, (Rossi, 1790)

Holloway, Graham J., Foster, Christopher W. & Herrmann, Andreas, 2024, The Genus Orphilus Erichson, 1846 (Coleoptera: Dermestidae) in Europe, The Coleopterists Bulletin 78 (2), pp. 117-124 : 121-123

ORPHILUS nIgeR (Rossi, 1790)

Orphilus niger ( Fig. 11A ): mean ♂ BL = 3.21 ± 0.23 mm (n = 14, max = 3.50 mm, min = 2.7 mm), mean ♂ BW = 1.96 ± 0.15 mm (n = 14), mean ♂ BW/EL = 0.887 ± 0.019 (n = 14). Mean ♀ BL = 3.29 ± 0.17 mm (n = 6, max = 3.5 mm, min = 3.05 mm), mean ♀ BW = 2.05 ± 0.14 mm (n = 6), mean ♀ BW/EL = 0.887 ± 0.020 (n = 6). Females do not have a significantly larger BL than males (t = 0.4, df = 16, ns), and BW does not vary between the sexes (t = 0.71, df = 16, ns). There is no evidence of a difference in shape (BW/EL) between males and females (t = 1.15, df = 16, ns). The integument is heavily punctate, and the elytra have a slight reddish hue. The reddish coloration of the elytra is most noticeable in dissected specimens, less so otherwise.

The antenna ( Fig. 11B ) is reddish brown, asymmetrical, and pubescent. The example shown in Fig. 11B is 192 µm long and 139 µm across antennomere 10.

The dorsal surface of the aedeagus ( Fig. 12A ) is hollowed out so that the outer margins of the parameres form ridges. The paramere margins are parallel until about halfway where they bulge outwards slightly before sweeping in towards pointed tips at the posterior end. The median lobe is broad across its base and remains approximately parallel-sided for about half of its length before abruptly narrowing and continuing, again nearly parallel-sided to a pointed tip. In lateral view ( Fig. 12B ), there is no clearly defined tooth on the ventral surface of the tip of the median lobe. The soft tissue continues along the length of the median lobe. The median lobe forms a gutter with the soft tissue spanning the width of the gutter to create a tube, presumably through which sperm travel during mating.

The pale edges around the tips of the parameres ( Fig. 12B ) are covered in erect setae that sweep back towards the anterior end of the aedeagus.

The tips of the ovipositor styli are claw-like ( Fig. 13A ). The distance between the claws on each stylus in the example shown in Fig. 13A is 35 µm. The anterior claw of each stylus is heavily sclerotized and dark, much darker than the posterior claw (most easily seen in Fig. 13B ). Two setae are positioned on the tip of each stylus. Tergite X is only slightly bilobed with the posterior and lateral surfaces covered in long setae ( Fig. 13B ).

Records of O. niger extend from the Iberian Peninsula across southern Europe and into Asia, according to Háva (2023a) as far as Kyrgyzstan ( Fig. 14 ). The single record of O. kabakovi is shown in Fig. 14 (Háva and Kadej 2014).

Morphometric Comparison. BL varied significantly among species (F 3, 135 = 13.49, p <0.001). Orphilus aegeanus (mean BL = 3.51 mm), O. africanus (mean BL = 3.3 mm), and O. beali (mean BL = 3.56 mm) were not significantly different, but O. niger (mean BL = 3.24 mm) was significantly smaller than O. aegeanus and O. beali . There was a marginally significant difference between male and female BL (F 3, 135 = 2.67, p = 0.05), with males smaller than females.

BW/EL was derived as a measure of body shape, with EL measured rather than BL for increased accuracy (sometimes a gap was present between the pronotum and the elytra). There was significant variation among species for BW/EL (F 3, 137 = 36.44, p <0.001), with O. beali being significantly broader (mean BW/EL = 0.931) than O. aegeanus (mean BW/EL = 0.883), O. africanus (mean BW/EL = 0.893), and O. niger (mean BW/EL = 0.890). There was no difference in BW/EL among O. aegeanus , O. africanus , and O. niger . There was no significant difference in BW/EL between the sexes (F 3, 137 = 1.95, ns).

Figure 15 combines the BL and BW/EL data for all four species. There is considerable overlap among the species, especially O. aegeanus , O. africanus , and O. niger . Orphilus beali is larger than the other three species and with a broader profile, but even so O. beali still overlaps the data from the other three species. Figure 15 suggests that Orphilus specimens from Europe with BL> 3.7 mm and/or BW/EL> 0.92 are likely to be O. beali .

Figures

Fig. 11. Orphilus niger. A) Habitus, dorsal aspect (scale bar = 1 mm), B) Antenna (scale bar = 100 µm).

Fig. 12. Orphilus niger aedeagus. A) Dorsal aspect, B) Lateral aspect. Scale bars = 100 µm.

Fig. 13. Orphilus niger ovipositor and tergite X. A) Lateral aspect, B) Dorsal aspect. Scale bars = 100 µm.

Fig. 14. Distributions of Orphilus niger and O. kabakovi. Hatched areas indicate countries from which O. niger is found according to Háva (2023a). Records supplemented with other specimens in AHEC dissected prior to the current study.

Fig. 15. Body width/elytra length (BW/EL) plotted on body length (BL: mm) for Orphilus aegeanus (blue dots), O. africanus (green dots), O. beali (orange dots), and O. niger (yellow dots).