Polyphylla anivallis La Rue, 2016

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 : 4-7

Polyphylla anivallis La Rue , new species

( Fig. 1–5 , 50–51 )

Type material. Holotype. Male ( CASC #18361 ). Labeled “ USA, NEW MEXICO: Hidalgo County, 3 mi E. Jct. St. Hwys. 338 & 79, Diamond-A-Ranch - Juniper Trap, sand dunes, 25-26.VII.2005 // 1584m elev., Oak-Juniper-Mesquite, D.A. La Rue collector, 175w HgVL.” Paratypes. (32). Labeled as holotype (31 males); “ USA, NEW MEXICO: Hidalgo County, 3 mi ENE Fitzpatricks, 5-6.VIII.2002, 1585m, K.H. Osborne collector, MV” (1 male). BYUC, CASC, JWSC, MXAL, PESC, PHLC, POKC, RACC, RHMC, SBMNH, UCRC .

Description. Holotype. Male ( Fig. 1–4 ). Length 19.5 mm. Greatest width 9.0 mm. Humeral width 8.0 mm. Form. Elongate, parallel-sided, diminutive. Color. Head, eyes, pronotum, protibial dentition black; antennomeres, other appendages of head, scutellum, and legs rufotestaceous; elytral integument black, deep rufotestaceous to rufopiceous under magnification (10.5×); pygidium, pterothoracic integument, exposed abdominal sternites rufopiceous; except where noted, setal and squamal vestiture pale yellow. Head. Subconvex; clypeus transverse with strongly reflexed, bisinuate anterior margin; anterior angles obtuse, lateral margins convergent basally; disc deeply concave, coarsely punctate, with long, suberect setae and acuminate scales. Frontoclypeal suture sinuate, obscured medially by coarse punctation. Frons and vertex shallowly punctate, provided with long, erect, setae. Maxillary palpomere-4 cylindrical, anteriorly depressed, finely rugose with translucent, golden yellow setae; subequal in length to three basal palpomeres combined. Mentum subquadrate, anteriorly emarginate, angles broadly rounded. Antennae. Scape elongate, distally bulbous, convergent basally, provided with a dense scopula of long setae; lamellate antennomeres 4–10 distally curved obtusely outward, provided with randomly distributed translucent, golden yellow setae. Antennal club 2.7× (linear measurement) or 4× (curvilinear measurement) longer than basal antennomeres combined. Pronotum. Strongly convex, transverse, 2.5× wider than length at midline, widest at posterior 1/2; anterior angles obtuse, basal angles broadly arcuate and explanate; marginal bead lacking anteriorly, feebly reflexed and coarsely serrate posterolaterally, evanescent posteriorly. Disc coarsely to moderately punctate; punctures provided with either a single, recumbent, acuminate scale or long seta; medially sulcate dividing a transverse tumidity; appearing trivittate, medial vitta longitudinally complete, lateral vittae eroded at apical 1/2, basally formed as two distinct patches of imbricate, white scales. Scutellum. Oblong, broadly rounded; margins glabrous, disc medially provided with solitary to imbricate, acuminate white scales. Elytra. 3.2× greater in length than width; humeral angles obtusely rounded, posterolateral angles broadly arcuate and feebly explanate. Marginal bead evanescent posterolaterally, sutural bead posteriorly cristate with apices acuminately produced. Disc moderately to coarsely punctate; calli gibbous, impunctate; vestiture composed of acuminate scales and widely scattered, suberect setae; appearing nearly avittate, an indication of vittae composed of widely separated glomerate patches of contiguous to imbricate, acuminate, white scales and suberect setae. Metathoracic wings functional. Pygidium. Subtriangular, convex, length subequal to width; distal apex broadly rounded; disc coarsely punctate, vestiture composed of acuminate scales and suberect setae. Venter. Densely pubescent obscuring pterothorax; exposed abdominal sternites convex, penultimate and ultimate sternites with a basal glabrous band; vestiture composed of solitary to imbricate acuminate, white scales and scattered, suberect setae throughout. Legs. Protibia strongly bidentate, basal third tooth feebly indicated as an angular projection; dentition widely separated, projecting obliquely forward from longitudinal tibial axis; inner margin with a coarse, serrated ridge; outer margin with a longitudinal carina; surfaces coarsely to finely punctate, variably covered with solitary to contiguous acuminate scales and scattered setae. Meso- and metatibia with an incomplete transverse carina; dorsally coarsely to finely punctate, margins diverging toward apex at distal 1/3, provided with a fringe of thick spiculae. All femora flattened, margins parallel, surface vestiture as in protibiae. Apices of tarsomeres coronate with a fringe of short, translucent spiculae; tarsomere-5 elongate, subequal in length to four basal tarsomeres combined, ventral surface bearing a sharp 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, apices convergent; median notch sharply rounded, separated approximately 1/2 length of parameres; lateral aspect, apical 1/3 cristate; apices smoothly rounded ventrally; caudal aspect, subconvex, obliquely depressed; distal tips nearly adjoined anterodorsally.

Female. Unknown.

Variation. Males (32). Length 17.0– 20.5 mm. Greatest width 8.0– 10.5 mm. As holotype except: Color. Scutellum, antennal scape and protibial surface black. Head. Clypeus feebly emarginate anteriorly, angles rounded. Pronotum. Lateral marginal bead feebly serrate, angulate medially; setal vestiture densely distributed. Scutellum. Setal and squamal vestiture reduced. Elytra. Vittae represented as a linear pattern of solitary to contiguous scales or with short vittal fragments; setal vestiture reduced (abrasion?). Pygidium. Setal vestiture reduced. Venter. Squamal vestiture of exposed abdominal sternites obscuring surface. Legs. Distal tips of protibial dentition worn.

Diagnosis. The avittate elytral vestiture and black to deep brown dorsal integument of P. anivallis are similar to P. stellata Young ( Fig. 45 ). Some specimens of P. anivallis have discontinuous elytral vittal fragments with edges coarsely eroded ( Fig. 5 ), whereas, males of P. stellata have at most small, irregular-shaped spots of contiguous to imbricate squamae in normally vittate areas. In addition, protibial dentition in male P. stellata varies from bidentate to tridentate (bidentate in P. anivallis ); and lacks the cristate elytral sutural apices of P. anivallis . The presence or absence (presumably abraded) of elytral discal setae is variable in P. stellata (present in P. anivallis ). Both species share a mixture of white and pale yellowish-brown elytral squamae; presence of pronotal and pygidial setae; and similar ecological requisites: P. stellata is associated with sandy alluvial substrates of the American, Sacramento, and San Joaquin River Deltas, Contra Costa to Sacramento Counties, California ( La Rue 1998) while P. anivallis is restricted to a geographically isolated sand dune complex in the Chihuahuan Desert of southwestern New Mexico. These morphological similarities may be the result of identical adaptive solutions to similar environmental pressures prevalent in psammophilous ecosystems.

In dorsal habitus and distribution, P. anivallis may be confused with avittate concolorous P. diffracta (s.l.). However, that species is devoid of elytral setae; has light yellowish brown to dark brown (rarely olivaceous) integumental color; white (rarely yellow) squamae; and absence of acuminately produced elytral sutural apices. Ecologically, P. diffracta (s.l.) is a highly facultative species.

Natural history. Polyphylla anivallis is ecologically associated with relictual pinyon-juniper-oak woodland refugia growing in deep semi-stabilized, low relief sand dunes ( Lanner and Van Devender 1981; Thompson and Anderson 2000; Smith and Farrell 2005).

Adult emergence of P. anivallis is apparently prompted by the onset of the summer monsoon that typically begins during July, indicative of “phenotypic plasticity” (i.e. any change in an organism’s characteristics in response to an environmental signal, Schlichting and Smith 2002). Earlier collection attempts during the drier months of May and June were unsuccessful. At the time the type series was collected, during late July, there were standing pools and puddles of monsoonal rain throughout the area and the sand was damp to a depth of 2 to 7 cm. Just prior to dusk, in faint diffused light, males were observed flying rapidly in open areas between dune vegetation approximately one meter above the sand surface. Most males were attracted to a 175 watt mercury vapor light station while other males were encountered crawling on the sand surface after twilight. Females are unknown and presumed flightless.

Ecology. Animas Valley Sand Dunes ( Fig. 50–51 ) are located in the Chihuahuan Desert of southwestern New Mexico, 1580 m elevation. The northwest-southeast oriented basin where they occur is bordered on the west by the Peloncillo Mountains and the Animas, Pyramid and San Luis Mountains to the southeast. Due to internal drainage, most of Animas Valley contains fine textured Pleistocene alluvial deposits ( Kottlowski 1965). Sediments and alluvia, including those from two ephemeral playas, remnants of Pleistocene Lakes Animas and Cloverdale, are subject to saltation by southerly prevailing winds and subsequent downwind accretion at the southeast margin of the valley. These accumulations form diminutive rounded lunette dunes in an elongated arcuate-shaped mass which essentially follow the basal contours of the southern Animas Mountains. The pale ecru sand color is a result of this amalgam of aggregates.

A complex of transitional floristic elements representing Chihuahuan desert scrub, oak savanna, oak woodland, and pinyon-juniper woodland occur near or within the dunes. Dominant vegetation in the immediate habitat includes Quercus sp. (oak: Fagaceae ), Pinus engelmannii Carrière (apache pine: Pinaceae ), P. leiophylla var. chihuahuana Englemann (chihuahua pine: Pinaceae ), Juniperus deppeana von Steudel (alligator juniper: Cupressaceae ), Arctostaphylos sp. (manzanita: Ericaceae ), scattered Yucca sp. (Asparagaceae) , with an understory of numerous forbs and grasses depending on precipitation levels.

Climate is characterized by high amounts of solar radiation, wide diurnal ranges in ambient temperature, low relative humidity, and highly variable precipitation with subsequent elevated rates of evaporation. The dry early summer months of May and June are typically the hottest part of the year with average temperatures of 16° to 32° C. Winters are generally cool with average daytime temperatures between 4° and 14° C., and occasional snow at higher elevations. Average annual precipitation of 24 to 38 cm primarily occurs during July through September as brief localized convective thunderstorms. As much as 90% of annual rainfall occurs during this period ( Holmgren et al. 2003).

Conservation. Because of varied topography, unique floral diversity, and geographic isolation of Animas Valley, the ecoregion is recognized as a refugium for many threatened and endangered indigenous species ( Dinerstein et al. 2000). The area comprising the type locality is under the jurisdiction of the Diamond-A-Ranch (formerly the Gray Ranch) which is administered by the Animas Foundation, a private conservation agency dedicated to protecting the abundance of biological diversity and natural and historical values of the area. As a result, public access to the area is carefully regulated which affords P. anivallis some protection. However, because of its apparent endemicity, P. anivallis should be considered a species of “special concern.”

Etymology. From a combination of the prefix of “Animas” and the Latin vallis, “valley.”

Common name. The Animas Valley polyphyllan scarab beetle.

Figures

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

Figures 50–57. Habitats. 50–51) Polyphylla anivallis. Animas Valley Sand Dunes, Hidalgo Co., NM. 52–53) Polyphylla koso. Coso Mountains, Inyo Co., CA. 52) Coso Bridge. 53) Mill Springs Canyon. 54–55) Polyphylla morroensis. Baywood Fine Sands, San Luis Obispo Co., CA. 56–57) Polyphylla socorriana. El Socorro Sand Dunes, Baja California, MX.

Figures 42–47. Described females and comparative male. Polyphylla monahansensis Hardy and Andrews. 42) Male. 43–44) Female. Polyphylla stellata Young. 45) Male. 46–47) Female.