Phyllophaga (Listrochelus) baja Warner 2022, new species
Creators: name: Warner, William B.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Melolonthidae
Phyllophaga
Phyllophaga baja

description: Phyllophaga (Listrochelus) baja Warner, new species
Figures 1–6
Holotype male and allotype female (both deposited in the Instituto de Biología, Universidad Nacional Autónoma de México, D.F., México), and 11 paratypes (7♂, 4♀), all with data: “ Mexico: Baja California Sur; W side San José del Cabo; 23.049°, −109.719°; toll plaza lights on Hwy. 1D; ix-29-2003; W.B.Warner. ” Paratypes are deposited in Arizona State University, Tempe, AZ; Centro de Investigación Cientifica y de Educación Superior de Ensenada, Baja California, México; Florida State Collection of Arthropods, Gainesville, Florida; K.E. Schnepp collection, Gainesville, Florida, and the author’s collection.
Diagnosis. Subparallel, rufotestaceous, base of head lacking carina or ridge (Fig. 1); elytron ecostate and estriate except for tumid sutural interval; tarsal claws serrate along a single margin, in male without intervening larger tooth (Fig. 6), in female apically deeply cleft (Fig. 5); male genitalia complex (Fig. 2–4) bilaterally symmetrical, parameres bilobed in lateral view, sclerotized portion of aedeagus tubular, apically open and expanded “spathe-like.”
Description. Holotype male. Length: 9.5 mm. Width: 4.5 mm. Body elongate, subcylindrical, widest at about middle of elytra, dorsally glabrous, rufotestaceous, weakly shiny, elytron and abdomen lighter in color than head and pronotum. Head nearly contiguously punctate except for impunctate band at base, without transverse basal carina or ridge dividing punctured and impunctate area; clypeus very weakly bilobed, moderately reflexed, densely punctured as on head. Antenna 10-merous; antennomere 2 subovoid, appearing “inflated” and nearly as wide as scape apex; antennomeres 3–7 distinctly narrower; club about as long as to slightly longer than antennomeres 2–7. Pronotum widest and obtusely angulate at posterior two fifths, width about 1.6 times length, lateral margins straight and evenly weakly converging anterior and posterior to angle, sparsely punctate, punctures rather shallow, moderate in size, mostly separated by one to about five times their own widths, only slightly more dense near margins. Scutellum with lateral margins convex, apical angle nearly right, impunctate basomedially, finely and densely punctate along free submargin, punctures about half size of elytral punctures. Elytron slightly less than three times as long as pronotum, without striae except sutural interval swollen, making sutural stria weakly evident; disc punctured as in pronotum except punctures perceptibly deeper, lateral margin fimbriate, setae alternating long and short, long setae shorter than sutural interval. Pygidium weakly convex, subtriangular, punctures similar in size to those on elytra, except punctures more variably spaced and deeper, subocellate, mostly separated by about one-fourth to thrice their own diameters. Venter with thoracic sternites rather uniformly moderately setose, abdomen without strong sexually dimorphic characters though flatter in lateral view than in female, sparse setae mostly short and appressed, but with scattered longer setae laterally and apically; last visible abdominal ventrite with median carina distinct in about lateral thirds (Fig. 2), with weakly impressed submargin in about middle third. Anterior tibia tridentate on external margin, tarsi on all legs longer than their respective tibiae by length of terminal segment or (metatarsus) less; tarsal claws narrow, serrate along a single margin in basal two thirds, without any larger intervening tooth. Genitalia with parameres fused basally, complex, in lateral view dorsally deeply obliquely incised at about middle to form a short dorsal lobe and long ventral lobes, lobiform and narrower past incisure, in dorsal view with basal lobe truncate apically, medially produced into short, blunt protrusion that overhangs convex shelf connecting ventral lobes; ventral lobes divided in about apical half, pincer-like, lacking apical setae, dorsally with inner edges abruptly emarginated at basal two-fifths; sclerotized portion of internal sac tubular, tube subapically widened into dorsal spathe-like opening, opening subhexagonal, apex mucronate.
Allotype female. Length: 11.0 mm. Width: 5.0 mm. As in male except antennal club about as long as antennomeres 3 to 7 combined; abdomen more convex, last visible abdominal ventrite similar to that of male but more convex; all tarsal claws shorter, more strongly curved and deeply apically cleft and with ventral tooth ventrally serrate except apically, and dorsal ramus lacking serrations; genitalia: in ventral “in face” view with inferior plates smooth, subquadrate, superior plates subsemicircular, each with disc concave and quickly becoming membranous, with short marginal row of 4–5 long setae at apex of more darkly sclerotized, narrowly convex rim.
Variation. Males, length: 9.0– 10.5 mm, width: 4.0–5.0 mm. Females, length: 10.0–11.0 mm, width: 4.5–5.0 mm. Antennal club length and funicle segment shape varies slightly in the series, otherwise fairly uniform in appearance.
Etymology. This species is named for the colloquial abbreviation for the Baja California peninsula, “Baja,” a Spanish adjective used in this sense as a noun, and here as a noun in apposition.
Habits. Unknown: the type series was collected under mercury vapor lights of the only toll booth at the time on the Los Cabos Airport to Cabo San Lucas tollway.
Relationships. Based on genital form, this species is apparently most closely related to Phyllophaga oblonga (Bates) and P. seri Morón, sharing similarly complex parameres of a form different from other species in the complex, being distinctly bilobed in lateral view and lacking apical setae, though in the paramera of P. baja the medial excavation much narrower than those other two species. Interestingly, specimens of P. baja lack the crenate lateral pronotal margins as in those species, have 10-segmented antennae, vs. 9-segmented antennae as in those species, and have the last visible abdominal ventrite (“anal plate” of Morón 2002) with its medial carina distinct laterally. Because of such differences, P. baja does not go past couplet 2 in Morón’s (2002) key. The apically cleft female tarsal claws are very unusual in form for the subgenus, and is unique within the timida group.
description: Published as part of Warner, William B., 2022, A new Phyllophaga (Listrochelus) timida group species from Baja California Sur (Coleoptera: Scarabaeidae: Melolonthinae), pp. 1-4 in Insecta Mundi 2022 (943) on pages 1-3, DOI: 10.5281/zenodo.7300582