Polyphylla uteana Tanner, REINSTATED STATUS, 1928

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 : 20-25

Polyphylla uteana Tanner, REINSTATED STATUS

( Fig. 28 , 33–41 )

Polyphylla uteana Tanner 1928:276 .

Type locality. “Kanab, Utah, about thirty miles southeast of Zion Park” [Kane County].

Type repository. V. M. Tanner Collection, BYUC #25 . Holotype. Male. [examined].

Comments on the holotype. Male. Labeled ( Fig. 37 ) [in descending order] (1) “Kanab, Utah ” rectangular, white, black type-set; (2) “Anson Call Jr.” rectangular, white, black type-set; (3) “3168” rectangular, white, hand-printed in pencil; (4) “25” square, white, black type-set; (5) “Type” hand-printed perpendicular at left margin, “ Polyphylla uteana Tanner ” with male gender symbol at lower left corner, rectangular, red with black border, hand-printed in black ink.

No label reference to a collection date is present, however, Tanner (1928) stated “ July 13, 1927 ” as well as an additional collector: “D. Irvin Rasmussen.”

The holotype is an aged specimen, abraded anterodorsally, with heavily worn protibial dentition, and the left apical fourth and fifth metatarsomeres missing.

It is briefly characterized as follows: Length 25.0 mm. Greatest width 14.5 mm. Head and pronotum piceous; elytra deep rufotestaceous, grading to rufopiceous at humeri; pygidium, exposed abdominal sternites, and legs rufotestaceous; antennae and other appendages of head light testaceous; squamal and setal vestiture pale white; head and pronotum moderately to deeply punctate; clypeal disc shallow, anterior margin slightly emarginate and weakly reflexed, lateral margins parallel; maxillary palpomere-4 3/4 length of three basal palpomeres combined; head, pronotal, elytral, and pygidial discs bearing setae; elytral sutural apices feebly acuminose; disc nearly avittate, vittae heavily eroded; protibia bidentate, dentition widely separated, significantly worn (age and abrasion), indicated by short protuberances; tarsal claws with basal proximal tooth.

Tanner (1928) stated “pronotum without erect hairs,” presumably referring to the central pronotal disc that is heavily abraded ( Fig. 35 ). However, under magnification (10.5×), there are thin, recumbent, pale setae randomly distributed on the pronotal disc. Also, he regarded the protibial dentition as unidentate. Although heavily worn, there are two distinct remnants of dentition on each protibia.

Taxonomy. According to the original description ( Tanner 1928), P. uteana was based on a single male specimen labeled “Kanab, Utah.” Young (1967, 1988) synonymized P. uteana with P. diffracta based on the purported similarity of the “relative size of the antennal club, lack of elytral hairs, closely punctate pronotal disc, and a ‘unicolorous black’ ( Young 1967) or ‘unicolorous brown’ ( Young 1988) elytral coloration.” In comparing it to P. hirsuta, Young (1967) stated that P. uteana was “totally without vittae.”

Contrary to Young’s observations, however, upon closer scrutiny and magnification (20×), there are, in fact, short, suberect, randomly distributed, pale setae present on the elytral surface of the holotype. In addition, the specimen is distinctly bicolored displaying a deep rufopiceous head and pronotum, and deep rufotestaceous elytra with vestiges of former vittae ( Fig. 33–36 ), clearly in contrast to Young’s evaluation.

The holotype of P. uteana is conspecific with, and well within the morphological range of variation of, specimens from the Coral Pink Sand Dunes, Kane County, Utah, approximately 12 km (7.5 air miles) west of Kanab, the type locality. In addition, molecular sequence data of mitochondrial 16S, COI, and COII cytochrome oxidase genes of this deme ( Russell 2000) conclusively establishes the distinctness of this species and strongly supports reinstatement to species status.

Remarks. The known range of P. uteana appears to represent a southwest to northeast morphological cline which also corresponds to the dune slip-face orientation and eolian migration alignment.

Males from the southwest lower dune field (~ 1600 m elevation) ( Fig. 40 ) display lighter integumental coloration (light testaceous to rufotestaceous); coarsely eroded, fragmented elytral vittae; lamellate antennomeres strongly recurved, nearly attaining a right-angle; and shorter overall body length (<22.0 mm). Ecologically, this area is a mixed Mountain-Brush plant community primarily within semistabilized barchanoid dune hummocks.

Males from the northeast upper dune field (~ 1900 m elevation) ( Fig. 3–39 ) tend to be darker in coloration (deep rufotestaceous); consistently avittate; lamellate antennomeres feebly recurved; and greater in body length (> 22.0 mm). Collection localities from this area are in pinyon/juniper uplands in stabilized or active parabolic and transverse dune types.

The coloration of P. uteana closely resembles the distinctive sand color particularly during crepuscular hours, at low solar angle, when adults are most active suggesting predator evasion adaptations through parasematic crypsis or spectral properties in flight. For desert arthropods, crepuscular activity may be an effective way of avoiding thermal stress and/or predation while still utilizing available light.

Based on morphological similarities, Tanner’s holotype was most likely collected somewhere in the northeast upper dune field within the Sand Hills region where large areas of arenaceous substrates are common. The specific locality of “Kanab, Utah ” may have been used simply because it was the closest point of reference since very few roads, towns or other geographic points were established in this area of south-central Utah during the early part of the twentieth century. This was common practice as early collectors and authors were less precise about specimen labeling methodologies as compared to modern standards. Usually, a nearby town, prominent landmark or geographic form were used as demonstrated by Tanner’s reference (1928), “about thirty miles southeast of Zion Park.”

Materials examined. In addition to the holotype, 85 males and 2 females variously labeled “ USA, Utah: Kane County, Coral Pink Sand Dunes ” with dates and additional data as follows: 14.VII.1991, G.R. Ballmer (4 males, UCRC) ; Ponderosa Grove Campground , 8.VII.1992, R.W. Baumann (18 males, BYUC), L.J. Liu (5 males, BYUC), J.T. Zenger (12 males, BYUC) ; 2.5 rd. mi. NE Jct. Hancock Rd. and Coral Pink Sand Dunes Rd., County Road 43, 25.VI.1993, R.A. Cunningham, J.D. Beierl (10 males, 1 female, RACC) ; 10.VII.2005, 1827m elev., N 37°02’33” W 112°43’32”, D.A. La Rue, 175w HgVL (36 males, 1 female “dune hummocks at dusk”, DALC) .

Redescription. Males ( Fig. 38–40 ). Length 18.0– 24.5 mm. Greatest width 10.0– 15.5 mm. Humeral width 9.0– 11.5 mm. Form. Elongate, robust, subparallel-sided. Color. Head, eyes black; pronotum deep rufopiceous to rufotestaceous; pygidium, tibiae, tarsomeres, exposed abdominal sternites and appendages of head rufotestaceous; scutellum and elytra deep rufotestaceous to light testaceous; pterothoracic integument and antennae light testaceous; except where noted, setal vestiture pale yellow, squamal vestiture white. Head. Convex; clypeus transverse with reflexed bisinuate anterior margin; anterior angles obtuse, lateral margins parallel to subconvergent basally; disc depressed, coarsely punctate, densely setose with dense setae and imbricate, acuminate scales. Frontoclypeal suture obscured by rugose punctuation, suberect setae and contiguous, acuminate scales. Frons evenly convex, surface coarsely, punctate; provided with contiguous to imbricate, acuminate scales and long, suberect setae. Vertex glabrous and shining. Maxillary palpomere-4 elongate, cylindrical, anteriorly depressed, apex truncate, densely setose with minute, golden yellow spiculae, 2/3 to subequal in length to three basal palpomeres combined. Mentum subquadrate, anteriorly emarginate, angles broadly rounded, disc deeply depressed, rugosely punctate, posterolaterally with long setae and acuminate squamae. Antennae. Scape short, constricted basally, apex bulbous, provided with a dense scopula of long, golden yellow setae; lamellate antennomeres 4–10 distally recurved obtusely outward, provided with scattered setae. Antennal club 2.2× (linear measurement) or 2.5× (curvilinear measurement) longer than basal antennomeres combined. Pronotum. Broadly convex, transverse, 2× wider than length at midline, widest at posterior 1/2; anterior angles obtuse, basal angles broadly arcuate and explanate; marginal bead absent anteriorly, heavily serrate posterolaterally, evanescent posteriorly. Disc coarsely to moderately punctate, an acuminate scale or long setae arising from each puncture; medially sulcate, dividing a transverse tumidity at posterior 1/2; trivittate; medial vitta longitudinally complete or coarsely eroded, when present, composed of contiguous to imbricate, acuminate scales; submarginal vittae eroded at apical 1/2, formed as two distinct glomerate patches of dense, imbricate, acuminate scales. Scutellum. Oblong, broadly rounded, margins glabrous, disc obscured by imbricate scales and long, suberect setae. Elytra. 2.4× greater in length than width; humeral angles obtusely rounded, posterolateral angles broadly arcuate. Marginal bead explanate and reflexed anterolaterally, evanescent posteriorly, sutural bead obscured by dense acuminate scales and suberect setae. Disc shallowly, rugosely punctate; calli tumose, coarsely punctate; vestiture composed of solitary to imbricate acuminate scales and long, recumbent to erect setae; avittate or with faint longitudinal squamal lines to the unaided eye, fragmented microscopically (10×). Metathoracic wings functional. Pygidium. Subtriangular, convex, length subequal to width, angles obtusely to acutely rounded; disc finely punctate, depressed behind reflexed margins; vestiture composed of contiguous, acuminate, scales and recumbent setae. Venter. Densely pubescent obscuring pterothorax; exposed abdominal sternites convex, depressed medially; with a basal glabrous band, vestiture composed of solitary to imbricate scales and scattered setae. Legs. Protibia bidentate, basal third tooth indicated as a slight angular projection; dentition widely separated, projecting obliquely forward from longitudinal tibial axis; inner margin rounded; outer margin with a raised, longitudinal dentiform carina; surfaces finely punctate with solitary, acuminate scales and scattered setae. All femora flattened, margins parallel, rounded anteriorly, surface vestiture as protibiae. Apices of tarsomeres coronate with a fringe of golden translucent spiculae, solitary setae, and acuminate scales; tarsomere-5 elongate, arcuate, ventral surface bearing a fine carina extending 1/2 length of tarsomere; tarsal claws with basal proximal tooth. Phallobase and parameres. Number examined (3). In dorsal aspect, symmetrical with two simple parameres narrowing distally, convergent at apical 1/3, apices diverging outward, median notch sharply rounded, subequal to 1/2 length of parameres; lateral aspect, apical 1/4 cristate, tapering to a faint carina length of median notch, apices smoothly rounded ventrally; caudal aspect, obliquely depressed outward; distal tips adjoined anterodorsally, acutely angled at apex.

Females ( Fig. 41 ). Length 19.5–22.0 mm. Greatest width 10.5–11.0 mm. Humeral width 8.5–9.5 mm. Excluding sexual dimorphic variation as male except: Form. Robust, ovate, widest at posterior 1/3. Color. Pronotum black to rufotestaceous; elytra, exposed abdominal sternites, pygidium, and tarsomeres brown to testaceous; legs rufotestaceous. Head. Clypeus broadly rounded, anterior margin arcuate; frontoclypeal suture absent; squamal vestiture sparse; lamellate antennomeres straight. Pronotum. Sharply convex; faintly trivittate; vittae fragmented, setal and squamal vestiture reduced. Scutellum. Medially with contiguous, acuminate scales and setae. Elytra. Vittae fragmented, forming indistinct lines; subhumeral vittae faintly indicated. Pygidium. Setal and squamal vestiture reduced exposing discal integument. Legs. Protibia strongly tridentate; dentition sharply acute, projecting obliquely forward from longitudinal tibial axis; mesotibial margin distally bearing two short projections.

Natural history. Males were first observed flying at or just before twilight and continued late into the evening except on one occasion ceasing abruptly at 23:15 hrs. PST when no additional males were seen at light stations nor encountered upon the sand surface. Similar to the behavior reported for P. aeolus ( La Rue 1998) and P. arguta ( Young 1988) . Although flight activity of P. uteana had ceased, males of P. arguta and P. decemlineata continued to be attracted to light stations for several hours.

Approximately 20 minutes prior to dusk, preceding male flight, female P. uteana were found crawling or stationary on the sand surface with antennae extended and lamellae in a splayed position. Despite attempts to induce flight by releasing them just above the sand surface, females would not fly suggesting they are flightless as in other Polyphylla species restricted to cryptic ecosystems ( La Rue 1998; Russell 2000; Skelley 2009). No adult feeding activity was observed and no specimen was encountered on vegetation. Adult longevity is presumably based upon metabolic reserves accrued during larval development. As in other psammophilous Polyphylla , adults of P. uteana undoubtedly spend diurnal hours at varied depths within the microenvironment of damp sand ( La Rue 1998).

Ecology. The Kanab and Coral Pink Sand Dunes are part of a larger sand dune regime located in the Colorado Plateau region of south-central Utah. The dunes are connected by sheet sand deposits to the Sand Hills region that extend northeast between Kanab Creek and the Sevier fault. Smaller sand accumulations have developed on the lee sides of numerous ridges, escarpments, and cliffs throughout the area. Estimates place the sand origin to the Pleistocene ( Gregory 1950) or possibly during the middle Holocene ( Shafer 1989). The salmon-colored sand is derived from a mixture of red and white Navajo Sandstone grains.

The vegetation at Coral Pink Sand Dunes is largely transitional with elements of cool desert shrub, pinyon-juniper, mountain brush, and ponderosa pine floral communities ( Welsh et al. 1993). Predominant species include Artemisia tridentata ssp. Nuttall (big sagebrush: Compositae), Juniperus osteosperma , and widely distributed Pinus edulis . A varied understory of extensive Calamovilfa gigantea (Nuttall) Scribner and Merrill (giant sand reed: Gramineae), Ericameria nauseous (Pallas) (rabbitbrush: Asteraceae ), Sophora stenophylla A. Gray (fringeleaf necklacepod: Leguminosae), and Wyethia scabra Hooker (rough mulesears: Compositae), with many annual species present at various times of the year depending on precipitation levels.

Climate is characterized as a cold desert (cold winters and hot, dry summers). Mean annual precipitation, which fluctuates greatly from year to year, averages 34.5 cm with occasional snowfall. In late summer, brief monsoonal cloudbursts are common. Ambient temperatures range from 7° to 32° C. In recent decades there has been increased available moisture but precipitation has become exceedingly variable ( Welsh et al. 1993).

Conservation. The major threat to P. uteana is habitat destruction from off-road vehicle activity which has greatly increased in recent decades. The use of three- and four-wheel off-road vehicles on the more vegetated dune areas adversely modifies and destroys critical habitat. Irreparable destabilization of vegetated dunes accelerates sand movement to a point that exceeds the tolerance of dune-adapted plants on which larvae of P. uteana are dependent. Surveys of other sand dune ecosystems in the Great Basin have established that P. uteana is endemic to a small region of contiguous sand dune areas in southcentral Utah. This would indicate that it is highly vulnerable to extinction from continued anthropogenic disturbance and should be considered a “critically imperiled” species.

Common name. The Coral Pink Sand Dunes polyphyllan scarab beetle.

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 33–41. Polyphylla uteana Tanner. 33–36) Holotype male. 37) Holotype labels. 38–40) Male variation. 41) Female.

Figures 1–5. Polyphylla anivallis. 1–4) Holotype male. 5) Left elytron of paratype male.

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

Figures 20–27. Polyphylla socorriana. 20, 22, 24–26) Holotype male. 21, 23, 27) Allotype female.