Apterocyclus honoluluensis Waterhouse, 1871

Paulsen, M. J. & Hawks, David C., 2014, A review of the primary types of the Hawaiian stag beetle genus Apterocyclus Waterhouse (Coleoptera, Lucanidae, Lucaninae), with the description of a new species, ZooKeys 433, pp. 77-88 : 79-80

Taxon classification Animalia Coleoptera Lucanidae

Apterocyclus honoluluensis Waterhouse, 1871 Figs 1-4, 12, 17

Apterocyclus honoluluensis Waterhouse 1871: 315. Type material: Lectotype male of A. honoluluensis (NHM) labeled: a) handwritten, "Kauai/ 4000 ft. / W.H. Pease / 71-29"; b) handwritten, "Apterocyclus / honoluluensis / ♀ (sic) Type C. Waterh. " c) red-bordered circular label “Type”; d) red paper, "Apterocyclus / honoluluensis ♂ / Waterhouse, 1871 / LECTOTYPE / des. M.J. Paulsen"; e) "Apterocyclus / honoluluensis / Waterhouse, 1871 / det. M.J. Paulsen 2012". Paralectotype of A. honoluluensis (NHM) = holotype of A. deceptor, below.

Apterocyclus deceptor Sharp in Sharp and Scott 1908: 405, synonymy confirmed. Type material: Holotype male of A. deceptor labeled: a) handwritten, "Kauai/ 4000 ft. / W.H. Pease / 71-29"; b) handwritten, "Apterocyclus / honoluluensis / ♂ Type C. Waterh. " c) red-bordered circular label “Type”; d) handwritten, "Apterocyclus / deceptor / Type D.S."; e) yellow paper, "Apterocyclus / honoluluensis ♂ / Waterhouse, 1871 / PARALECTOTYPE / des. M.J. Paulsen"; f) red paper, "Apterocyclus / deceptor ♂ /Sharp, 1908 / HOLOTYPE / des. M.J. Paulsen"; g) "Apterocyclus / honoluluensis / Waterhouse, 1871 / det. M.J. Paulsen 2012".

Apterocyclus feminalis Sharp in Sharp and Scott 1908: 405, synonymy confirmed. Type material: Holotype female of A. feminalis (NHM) labeled: a) handwritten, on cork "Platycerus feminalis, / typ. D.S. / Kauai, 4000 ft. VII-'96 / Perkins"; b) "Sandwich Is. / 1912-215"; c) red-bordered circular label “Type”; d) red paper, "Apterocyclus / feminalis ♀ /Sharp, 1908 / HOLOTYPE / des. M.J. Paulsen"; e) "Apterocyclus / honoluluensis / Waterhouse, 1871 / det. M.J. Paulsen 2012".

Apterocyclus varians Sharp in Sharp and Scott 1908: 404, synonymy confirmed. Type material: Holotype male of A. varians (NHM) labeled: a) handwritten, on cork "Mts: Waimea Kauai / 5000 ft. Perkins IV.1894 / A. varians / Type D.S."; b) red-bordered circular label “Type”; c) "Sandwich Is. / 1912-215"; d) handwritten, "varians Sharp"; e) red paper, "Apterocyclus / varians /Sharp, 1908 / HOLOTYPE / des. M.J. Paulsen"; g) "Apterocyclus / honoluluensis / Waterhouse, 1871 / det. M.J. Paulsen 2012".

Diagnosis.

This smallest species (14-17 mm, rarely up to 21 mm) can be readily distinguished by the presence of a short but distinct ocular canthus (Fig. 1), which is not present in the remaining four species. Otherwise, as lamented by Van Dyke (1922), there is great morphological variability in the species. In most specimens the protibia lacks any external teeth proximal to the apex. A few specimens of each sex exhibit a single weak external tooth on the protibia, unlike the majority of specimens for which the entire external margin of the protibiae is otherwise a useful diagnostic character. Based on the specimens studied there is also pronounced variability in males in surface sculpture (shiny vs. alutaceous) and mandibular shape. Some male specimens have mandibles with traces of additional internal teeth. Females are more strongly shiny and can be distinguished by their mandibles completely lacking internal teeth and their more spherical abdomens. Without additional collecting to better define the distribution and pinpoint potentially isolated populations it is not possible to determine if the morphological variation present is actually taxonomically important.

Distribution.

This was historically, and has been recently, the most commonly collected species. It is known from various localities in Kōke’e State Park.

Remarks.

Waterhouse (1871) examined two specimens collected by Harper Pease in the "Mountains of Kanoi", which may be a mistranslation of Kaua’i as we can find no locality with that name. Waterhouse considered the specimens to be a male and female. As indicated by Sharp ( 1908), both specimens actually are males. Waterhouse illustrated the “female” and Sharp ( 1908) considered that specimen to be the type of Apterocyclus honoluluensis (Fig. 1). We designate that specimen here as the lectotype of Apterocyclus honoluluensis , in agreement with ICZN recommendation 74B. The other specimen becomes a paralectotype of Apterocyclus honoluluensis , and it also is the holotype of Apterocyclus deceptor Sharp (Fig. 2). The holotypes of Apterocyclus deceptor , Apterocyclus feminalis (Fig. 3), and Apterocyclus varians (Fig. 4) are conspecific with Apterocyclus honoluluensis , and these synonymies proposed by Van Dyke (1922) are reconfirmed.

Van Dyke (1922) indicated that the larvae were formerly abundant in the soil, when hundreds could be encountered while digging. Mizunuma (2000) reported that the larvae feed in soil that contains the decomposing trunks of the leguminous tree Acacia koa A. Gray ( Fabaceae ). Mizunuma (2000) also described the larvae of Apterocyclus honoluluensis as being sensitive to, and killed by, high temperature. In 1972, Howden found evidence of heavy predation on adults of Apterocyclus honoluluensis by introduced mice, as might be expected for a flightless insect exposed to a novel terrestrial omnivore ( Howden 2008).