Clypeolus maritimus (Broun), 1993

Brown, Samuel D. J., Leschen, Richard A. B. & Groenteman, Ronny, 2025, A new species of the New Zealand endemic weevil genus Clypeolus Broun (Coleoptera: Curculionidae: Cryptorhynchinae), found attacking an invasive weed, white horehound (Marrubium vulgare L. Lamiales: Lamiaceae), Zootaxa 5717 (4), pp. 544-570 : 558-560

Clypeolus maritimus (Broun)

( Figures 51–56 )

Acalles maritimus Broun, 1893: 1236 . Type locality: Mokohinau Islands .

Clypeolus maritimus (Broun) Lyal, 1993: 68 .

= Acalles cryptobius Broun, 1893: 1236 (Synonymised by Lewis, 1902: 204). Type locality: Mokohinau Islands .

Diagnosis of maritimus form: Densely covered with overlapping light brown to moderate yellowish brown appressed scales and scattered erect scales on the pronotum and elytral interstriae ( Figures 51 and 52 ). Fascicles formed by clusters of erect scales present on interstriae 2 and 4 above the elytral declivity. Elytra relatively longer (about 1.3 times longer than wide). Rostrum curved in lateral view.

Diagnosis of cryptobius form: Densely covered with tessellate round yellowish white to yellowish grey scales, lacking erect scales on the pronotum and elytra ( Figures 54 and 55 ). Fascicles absent. Elytra relatively shorter (about 1.2 times longer than wide). Rostrum straight in lateral view.

Distribution: Known only from the Mokohinau Islands (ND). Specimens with similar morphologies have been collected from other islands in the Hauraki Gulf and around the Coromandel Peninsula, but subtle differences between these and the type series make assigning these specimens to C. maritimus uncertain.

Remarks: The two nominal taxa currently synonymised with each other were collected from the Mokohinau Islands by Andreas (“P.”) Fremming Stewart Sandager and were described by Broun in the same work ( Broun 1893), indeed on the same page (The holotype of C. veratrus was also collected at the same time and described in the same work). They were synonymised by Lewis (1902), who recognised A. maritimus as the male and A. cryptobius as the female. This action was followed, without further comment, by Hustache (1936) and Lyal (1993). As is clear from the photographs of the type specimens and the two diagnoses above, the type specimens differ substantially. Our first impulse was to remove C. cryptobius from synonymy as a valid species. However, examination of the six specimens available in NZAC shows that four of the five specimens corresponding to C. maritimus have been dissected and are males, while the only specimen of C. cryptobius in NZAC is a female. Most of these specimens are unlabelled, but one (undissected) specimen bears a label reading ‘Lewis Col.’ and the apparent age of the others suggests they were collected at a similar time to the type series. It is likely that these six specimens were, in fact, the specimens that Lewis obtained from Sandager ( Lewis 1902) and used to arrive at his decision to synonymise the two nominal species. This suggests that this species could be displaying a degree of sexual dimorphism hitherto unrecognised within Clypeolus .

Populations of Clypeolus on other islands around the north-east coast of the North Island exhibit morphologies similar to both of these nominal taxa. Specimens with smooth, tessellate scales corresponding to the cryptobius morphology are known from Rangitoto I., Cuvier I., and the Poor Knights Is. Specimens with fascicles on interstriae 2 and 4 above the elytral declivity and numerous erect scales on the pronotum and elytra, corresponding to the maritimus morphology, are known from the Noises Is, Hen and Chickens Is, Cuvier I., and Motutapu I. Further research will be required to ascertain whether C. maritimus is more widely distributed, or whether these populations represent additional species in the complex.

The islands around the northeast coastline of the North Island have populations of Clypeolus that exhibit immense variation. On Cuvier Island (CL), for example, at least five morphologies are represented. Some of these can be confidentely referred to as species like C. signatus and C. pascoei , while other morphologies resemble C. cryptobius , C. maritimus and C. veratrus , but not exactly. The complex interplay of restricted gene flow between populations of a highly morphologically plastic and sexually dimorphic species may be responsible for promoting these highly variable populations.

It is noteworthy that there are no recent specimens of any genuine C. maritimus from the Mokohinau Islands, despite insect collectors having visited the islands during the intervening period between its description and now. In particular, the prolific collector G. (Willy) Kuschel spent 4 days on the islands in the late summer of 1978 ( Esler 1978), yet no specimens of C. maritimus originating from this trip have been located. If this species is indeed restricted to the Mokohinau Islands, this puts it into a similar threat category as Geodorcus ithaginis (Broun) ( Coleoptera : Lucanidae ).

Figures

FIGURES 51–56. Clypeolus maritimus (Broun), type specimens of synonyms. Acalles maritimus Broun, 1893, lectotype: 51, dorsal view; 52, lateral view; 53, labels. Acalles cryptobius Broun, 1893, lectotype: 54, dorsal view; 55, lateral view; 56, labels. Figures not at the same scale.