Polyphylla avittata Hardy and Andrews, 1978

La Rue, Delbert A., 2016, Natural history, ecology, and conservation of the genus Polyphylla Harris, 1841. 1. New species from the southwestern United States and Baja California, Mexico, with notes on distribution and synonymy (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2016 (491), pp. 1-41 : 18-20

Polyphylla avittata Hardy and Andrews

( Fig. 28–32 )

Polyphylla avittata Hardy and Andrews 1978:1

Type locality. “ Utah, Washington Co., 6 mi. S of Hurricane, Hurricane Dunes.”

Type repository. Holotype. Male. CASC #13098 [examined].

Polyphylla ratcliffei Young 1986:49 NEW SYNONYMY

Type locality. “ Utah, Grand Co., 9 mi. NW of Moab.”

Type repository. Holotype. Male. CASC #15999 (not University of Idaho, Young 1986:49) [examined].

Notes on synonymy. The basis for this synonymy is that the putatively diagnostic characters of P. ratcliffei (differences of parameres, protibial dentition, and geographic distribution) are within the range of morphological variation of P. avittata , as determined by comparison of the types and other material examined from several institutional and private collections.

In the original description, Young (1986) stated that P. ratcliffei could not be distinguished from P. avittata solely upon external morphological characters. However, he separated the two species based on “unique” male parameres, differences in protibial dentition, and disjunct distribution: southwestern Utah ( P. avittata ) and east central Utah ( P. ratcliffei ). All three criteria are not diagnostic and vary intraspecifically as follows:

Parameres. Young (1986, 1988) considered the parameres in P. avittata asymmetrical (“unequal” Young 1986). In caudal aspect, he regarded the tips as dorsally cristate (i.e. bearing a raised carina, what Young referred to as a “dorsal flange”) with apices adjoined distally, whereas, in P. ratcliffei , he considered the parameres symmetrical (“equal” Young 1986) lacking any raised carina with the apices clearly separated.

Examination of geographically intermediate samples from Emery and Garfield Counties, Utah (21 males), 16 displayed some indication of cristate parameres. In all samples, the parameres were symmetrical with the dorsal surface obliquely depressed outward, in contrast to those illustrated by Young (1986:49 Fig. 7 ). Consequently, the genitalic differences between these two species are regarded as intraspecific variation and unreliable to validate species recognition on this character.

Protibial dentition. Cazier (1938) and Young (1988) indicated that protibial dentition was rarely applicable in distinguishing species and rejected the character as diagnostic because of intraspecific and geographic variation.

Hardy and Andrews (1978) stated that nine of twelve male paratypes of P. avittata exhibit an indication of a third protibial tooth, the other three apparently bidentate as in the holotype. Young (1986) remarked that protibial dentition of the holotype and four paratypes of P. ratcliffei varied from weakly (i.e. bidentate with some indication of a third protibial tooth) to strongly tridentate. Assessment of available samples clearly demonstrates that protibial dentition within these two species is entirely variable and without any geographic correlation. Eleven of 25 P. avittata examined showed a slight indication of a third basal tooth. The remaining 14 were bidentate as the holotype. Only one of four P. ratcliffei was distinctly tridentate with the remaining three samples bidentate. The third basal tooth indicated as a slight lateral flange. Geographically intermediate samples from Emery and Garfield Counties (19 males) were all bidentate.

Distribution. The amended distribution ( Fig. 28 ) establishes that both putative taxa are more widely distributed than previously recognized. As a result, distribution is irrelevant in separating these species as used by Young (1986, 1988). In effect, Young’s comparative material upon which P. ratcliffei was established actually represented geographical extremes of a single taxon, P. avittata . Accordingly, it is expected that with continued field efforts in intervening sandy environments, the distribution between both type localities will prove to be one relatively continuous track.

In view of the continuity of variation among available samples, the amended geographical range, and the absence of other morphological characters to distinguish the two taxa, there are insufficient criteria to warrant their separation into distinct species. On the basis of the above analyses, P. ratcliffei is reduced to synonymy with P. avittata .

Materials examined. In addition to the holotypes, 37 males labeled USA, Utah: Emery County, S. Temple Wash , Goblin Valley State Park , 8.VII.1995, Holmes and Liu (1 male) ; Garfield County, Calf Creek Campground, 7 miles S. of Boulder , Grand Staircase-Escalante National Monument , 10.VI.1978 (4 males), 4.VIII.1983 (1 male), 19.VI.1986 (5 males), R.W. Baumann ; 3.VI.2001, D.J. Cavan (2 males); 19.VI.2002, S.M. Clark, R.W. Baumann (8 males); Grand County, Arches National Park , 3.VII.1964, EDW [collector initials?] (1 male) ; 3 miles N of Moab , 5.VI.1993, Liu and Kremer (1 male); (all BYUC) ; San Juan County, Montezuma Creek Trading Post , no date or collector (2 males, BYUC) ; Washington County, Snow Canyon State Park , 14-15.VII.1978 (2 males), 30.VI.1986 (2 males), G.H. Nelson, at blacklight ( FSCA) ; Hurricane Dunes, 6 mi. SW Hurricane, Flora Tec Rd. , 28.VI.1986, 15w BL, R.A. Cunningham, D.A. La Rue (4 males, RACC) ; 26.VI.1993, R.A. Cunningham, J.D. Beierl (2 males, RACC) ; 12.VII.1993, no collector (2 males, BYUC) .

Conservation. The type locality of P. avittata, Hurricane Dunes , Washington Co., Utah ( Hardy and Andrews 1978) has recently been modified to create Sand Hollow State Park, which includes a 1,322 acre reservoir. Although remnants of the former dune field remain, there have been no provisions to constrain off-road-vehicle use to specific designated areas. It is probable that this population of P. avittata has already experienced irreparable habitat degradation and is likely in imminent peril of extirpation.

Figures

Figures 28–32. Polyphylla avittata 28) Distribution of P. avittata Hardy and Andrews (solid circles) and P. uteana Tanner (black vertical lines). 29–32) Variation of male. 29) Hurricane Sand Dunes, Washington Co., UT (topotype). 30) Goblin Valley State Park, Emory Co., UT. 31) Grand Staircase- Escalante National Monument, Garfield Co., UT. 32) 3 miles N of Moab, Grand Co., UT.

Figures 6–10. Polyphylla koso. 6–9) Holotype male. 10) Left elytron of paratype male.