Polyphylla morroensis 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 : 10-14

Polyphylla morroensis La Rue , new species

(Fig. 11–19, 54–55)

Type material. Holotype. Male ( CASC #18340 ). Labeled “ USA, CALIFORNIA, San Luis Obispo County, Los Osos, private residence, 20.VIII.2007, Baywood Fine Sands, Elev. 133’, M. Walgren ” [phallobase and parameres mounted on card] . Allotype. Female. ( CASC). Labeled “ USA, CALIFORNIA, San Luis Obispo County, Baywood Park, VII.1968, J.D. Pinto. ” Paratypes. (11). Labeled as holotype (1 male); as allotype (2 males); Los Osos, 05.VI.1979, C. Meichart (1 male); 07.VII.1980, D. Overman (1 male); 01.IX.1984, J. Wagner (1 male); 22.VII.1986, E.M. Saylor (1 male); private residence, various dates between 30.VII.-08.VIII.2008, M. Walgren, L. Andreano (2 males, 1 female); 11.VIII.2008, M. Walgren, L. Andreano, shopping center lights (1 male). CASC, RHMC, SBMNH, UCRC .

Figures 11–19. Polyphylla morroensis . 11, 13, 15–16, 19) Holotype male. 12, 14) Allotype female. 17–18) Section of male left elytron, dorsal aspect, illustrating distribution of interstitial squamae (150×). 17) Polyphylla crinita , dense. 18) Polyphylla morroensis , sparse.

Four additional male specimens excluded from the type series because of excessive damage labeled as holotype (3); USA, CALIFORNIA, San Luis Obispo County, Los Osos , vacant lot, 10.VIII.2008, M. Walgren, L. Andreano (1) .

Description. Holotype. Male (Fig. 11, 13, 15–16, 19). Length 28.0 mm. Greatest width 12.0 mm. Humeral width 11.5 mm. Form. Elongate, robust, parallel-sided. Color. Head, eyes, and exposed abdominal sternites black; pronotum, scutellum, and elytra deep olive green, rufopiceous to black under magnification (10.5×); pygidium deep rufotestaceous; basal antennomeres, other appendages of head, pterothoracic integument, and legs rufotestaceous; lamellate antennomeres light testaceous; except where noted, setal vestiture pale rubiginous brown to yellowish-brown; squamal vestiture white; interstitial squamae pale yellowish-brown. Head. Subconvex; clypeus transverse with highly reflexed bisinuate anterior margin; anterior angles obtuse, lateral margins reflexed and convergent basally; disc deeply concave, coarsely punctate, densely setose with long pale setae and imbricate, acuminate scales. Frontoclypeal suture rugosely punctate, obscured medially by dense setal vestiture. Frons depressed on either side of a longitudinal tumidity, surface moderately to coarsely punctate, densely setose with solitary acuminate scales. Vertex glabrous and shining. Maxillary palpomere-4 cylindrical, anteriorly depressed, apex truncate, finely punctate and densely setose with minute, golden spiculae, 1/3 length of three basal palpomeres combined. Mentum subquadrate, anteriorly deeply emarginate, angles broadly rounded, disc posterolaterally with long setae. Antennae. Scape subtriangular, constricted basally, apex bulbous, provided with a dense scopula of long setae; lamellate antennomeres 4–10 distally recurved outward attaining a right-angle, provided with translucent, golden setae. Antennal club 2.5× (linear measurement) or 3.3× (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 obtuse and explanate; marginal bead absent anteriorly, serrate and explanate laterally, evanescent posteriorly. Disc moderately to coarsely punctate, punctures provided with an acuminate, recumbent scale or suberect setae, medially sulcate, dividing a transverse tumidity at posterior 1/2; trivittate; vittae longitudinally complete, edges eroded, composed of contiguous to imbricate, acuminate scales. Scutellum. Oblong, broadly rounded, margins glabrous, disc obscured by imbricate scales; devoid of setae. Elytra. 2.2× greater in length than width; humeral angles obtusely rounded, posterolateral angles broadly arcuate. Marginal bead explanate and reflexed posterolaterally, evanescent posteriorly, sutural bead obscured by dense acuminate scales. Disc rugosely punctate; calli tumose, glabrous, moderately punctate; vestiture composed of solitary to imbricate, acuminate scales; devoid of setae; distinctly vittate; vittae narrow, edges coarsely eroded, composed of contiguous to imbricate, acuminate scales; sutural vittae incomplete; subsutural vittae fragmented and discontinuous; submarginal vittae complete; subhumeral vittae evanescent. Interstitial squamae evenly, sparsely distributed (Fig. 18), intermittently contiguous with vittae. Metathoracic wings functional. Pygidium. Subtriangular, convex, length subequal to width; angles obtusely rounded; disc moderately punctate, depressed behind reflexed margins; vestiture composed of contiguous, acuminate scales; devoid of setae. Venter. Densely pubescent obscuring pterothorax; exposed abdominal sternites subconvex with a basal glabrous band, vestiture composed of solitary to imbricate scales and solitary setae. Legs. Protibia bidentate, lacking any indication of a basal third tooth; dentition moderately separated, projecting obliquely forward from longitudinal tibial axis; inner margin rounded, outer margin with a sharp longitudinal carina, surfaces moderately to coarsely punctate with evenly distributed acuminate scales and long setae. All femora flattened, margins converging toward apex, surface vestiture as 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 short, fine carina basally; 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 less than 1/2 length of parameres; lateral aspect, parameres cristate length of median notch, apices smoothly rounded ventrally; caudal aspect, obliquely rounded; distal tips separated, acutely angled, diverging outward at apex.

Allotype. Female (Fig. 12, 14). Length 24.5 mm. Greatest width 12.5 mm. Humeral width 12.0 mm. Excluding sexual dimorphic variation as holotype except: Form. Robust, ovate, widest at posterior 1/3. Head. Anterior clypeal margin deeply bisinuate, lateral angles sharp; basal antennomeres approximately 2.5× longer than lamellate club. Pronotum. Sharply convex; disc densely covered with long yellow setae; feebly trivittate; lateral vittae agglomerate, composed of contiguous to imbricate acuminate scales. Scutellum. Bearing a dense scopula of pale setae. Elytra. Subdiscal vittae interrupted at posterior 1/3; interstitial squamae lanceolate in form. Pygidium. Setae present at posteriorly margin. Legs. Protibia strongly tridentate, projecting perpendicular to longitudinal tibial axis; right protarsomeres-4 and 5, left and right metatarsomeres missing; metatibial dorsal surface with two prominent dentiform projections.

Variation. Males (12). Length 22.0– 27.5 mm. Greatest width 11.5–13.0 mm. As holotype except: Color. Elytra rufo-olivaceous. Pronotum. Medial vittae eroded. Scutellum. Squamal vestiture reduced or confined medially. Elytra. A shallow parascutellar sulcus present in some specimens. Pygidium. Long setae present.

Female (1). Length 23.0 mm. Greatest width 12.5 mm. Remarkably similar to allotype except: Color. Legs testaceous, protibial dentition black. Pronotum. Vittae more pronounced. Pygidium. Devoid of setae.

Diagnosis. The combination of deep olive green dorsal coloration; sparsely distributed yellowish-brown elytral interstitial squamae (Fig. 18); reddish-brown to deep yellowish-brown setae; narrow elytral vittae with coarse edges; evanescent submarginal vittae; and long, densely distributed pronotal setae (Fig. 15–16, 19) are sufficient to distinguish P. morroensis from all other species of Polyphylla .

Polyphylla morroensis may possibly be confused with P. crinita or its adelphotaxon, P. nigra , that are similar in general appearance. Males of those species have a black, reddish-black, or brown (sometimes olivaceous yellowish-brown in P. crinita ) dorsal integument; pale yellow to yellowish-brown setae; densely distributed elytral interstitial squamae (Fig. 17); elytral vittae with sharply defined ( P. nigra ) or uneven ( P. crinita ) edges; submarginal vittae longitudinally complete; and sparsely distributed pronotal discal setae. The presence ( LeConte 1856; Horn 1881; Casey 1914; Fall 1928, Hardy 1981) or absence ( Young 1988) of pronotal discal setae in male P. crinita is apparently subjective and open to interpretation as is the presence of elytral discal setae (present in syn. P. ruficollis perversa Casey 1914 ).

Both P. crinita and P. nigra are distributed from the Pacific northwest to Baja California, Mexico, and are associated with a variety of habitats including mixed conifer forest, mixed riparian woodland, ancient volcanic soils, and urban environs indicating diverse facultative ecologies.

Due to its littoral proximity, the dark olive green coloration; reduced, sparsely distributed interstitial vestiture; and narrow, eroded vittae of P. morroensis may be a selective response to the cooler, moist, coastal environment.

Natural history. Males of P. morroensis were collected at lights of private dwellings and a shopping center complex immediately adjacent to areas of open Baywood Fine Sands habitat. Females are presumed flightless as none were encountered at lights but were found within their burrows 5 to 7.5 cm below the soil surface by observing male flight behavior. Polyphylla decemlineata was encountered in the coastal-dune scrub floral community south of the Baywood Fine Sands ecosystem but was not sympatric in the known distribution of P. morroensis (M. Walgren, in litt.).

Ecology. Baywood Fine Sands ( Fig. 54–55 ) are located on the southeast shore of Morro Bay, San Luis Obispo County, on the central California coast. The sand dunes were deposited during the Pleistocene when eustatic sea levels were approximately 10 to 170 meters lower than at present exposing continental shelf sands to eolian accretion further inland ( Cooper 1967; Orme 1990; Knott and Eley 2006).

The sand appears dark grayish brown to dark brown with fine particle size corresponding to high organic content. These deep, well drained soils provide the foundation for an endemic coastal ecosystem that supports remnants of maritime chaparral and coastal-dune scrub floral communities including several federal- and state-listed endangered or threatened species.

Areas of maritime chaparral are dominated by a dense canopy of Arctostaphylos morroensis Wieslander and Schreiber (morro manzanita: Ericaceae ), a federally endangered species. Understory vegetation is minimal as the environment under this chaparral complex is one of negligible solar penetration and deep leaf litter. In some areas Ceanothus cuneatus (Hook) Nuttall (buckbrush: Rhamnaceae ), Eriophyllum confertiflorum de Candolle A. Gray (golden yarrow: Compositae), Mimulus aurantiacus Curtis (monkey flower: Phrymaceae ), Prunus fasciculata var. punctata Jepson (desert almond: Rosaceae ), Quercus agrifolia Nee (coast live oak: Fagaceae ), and Salvia mellifera Greene (black sage: Lamiaceae ) are present (M. Walgren, in litt.).

Coastal-dune scrub is the most imperiled habitat because of its location on relatively flat terraces adjacent to the Pacific Ocean where development is prevalent. During different seasons, Abronia umbellata Lamark (pink sand verbena: Nyctaginaceae ), Amsinkia spectabilis Fischer and Meyer (seaside fiddleneck: Boraginaceae ), Corethrogyne filaginifolia (Hooker and Arnott) Nuttall (california aster: Asteraceae ), Ericameria ericoides (Lessing) Jepson (goldenbush: Asteraceae ), Eriogonum parvifolium Smith (coast buckwheat: Polygonaceae ), Eriophyllum staechadifolium la Gasca (yellow yarrow: Asteraceae ), and numerous other ephemeral annual species predominate. The floral community is threatened by the invasive exotic, Ehrharta calycina Smith (veldt grass: Poaceae ), which supplants native species and can cover the dunes in dense expanses (M. Walgren, in litt.).

Ambient climate is characterized as subhumid mesothermal with cool, foggy summers and cool, moist winters. The climate provides frequent periods of fog drip that is a critical factor in limiting the distribution of endemic species of the ecosystem. Mean annual precipitation is approximately 37 cm at the coast to nearly 90 cm further inland. Average annual temperature is 5.5° to 26° C., with an average of 250 to 350 frost-free days. Elevation ranges from mean sea level in areas adjacent to Morro Bay, at the northwest margin of the dunes, to approximately 250 m in the southern dune area.

Conservation. The major threat to P. morroensis is urban development. Much of the area with moderate topographic gradients supporting Baywood Fine Sands has been subject to unprecedented urban expansion. In addition to direct removal and modification of the habitat, development has had detrimental effects on the quality of remaining habitat including fragmentation, deterioration due to increased recreational activity, and the introduction of invasive non-native vegetation (M. Walgren, in litt.).

Remnants of the dunes support several federal- and state-listed endangered or threatened species including Helminthoglypta walkeriana (Hemphill) (morro shoulderband snail: Helminthoglyptidae ), Anniella pulchra Gray (silvery legless lizard: Anniellidae ), Dipodomys heermanni morroensis (Merriam) (morro bay kangaroo rat: Heteromyida), Eriodictyon altissimum P.V. Wells (indian knob mountainbalm: Hydrophyllaceae ), and A. morroensis , clearly emphasizing the unique composition of the ecosystem.

Because of limited geographic range and imminent threat of extirpation from habitat modification, P. morroensis should be considered a “critically imperiled” species.

Etymology. From a combination of “Morro” and the Latin adjectival suffix - ensis, “originating in or from.”

Common name. The Morro Bay polyphyllan scarab beetle.

Figures

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.