Gracilivectura pygidialis Mayor and Gimmel, 2024

Mayor, Adriean J. & Gimmel, Matthew L., 2024, Two New Genera and Three New Species of Dasytinae (Coleoptera: Melyridae) from the Southwestern United States and Mesoamerica, The Coleopterists Bulletin 78 (1), pp. 33-52 : 49-51

Gracilivectura pygidialis Mayor and Gimmel , new species zoobank.org/ urn:lsid:zoobank.org:act:9C179575-6D1B-4E9C-B124-2430207AC4D9 ( Figs. 38–43 , 47–53 , 55–59 , 65–69 )

Diagnosis. Males of this species are easily distinguished from those of the only known congener, G. mojavensis , by the shape of the pygidium ( Figs. 38 , 55 ), which is deeply and broadly emarginate and the metatibia, which is widest at midlength and narrower in the apical half ( Fig. 49 ). Both males and females may be distinguished by the relatively sparse setae not obscuring the color of the cuticle dorsally ( Figs. 38, 41 ).

Types. Holotype ♂, deposited in CAS (holotype # CASTYPE 21603), labeled “ USA: CA: Imperial Co. \ 7.3 mi. SE of Ocotillo \ on I-8 West ; elev. 525 m. \ N32°41′38.6′′, W116°5′14.0′′ \ 16 March 2017; A. J. Mayor [white printed label] // Collected beating \ flowers of \ Hyptis emoryi [white printed label] // HOLOTYPE ♂ \ Gracilivectura \ pygidialis \ Mayor & Gimmel [red printed label]” . Paratypes, 66 specimens listed in the Type Specimens Examined section, with the additional label “ PARATYPE \ Gracilivectura \ pygidialis \ Mayor & Gimmel [yellow printed label]” .

The holotype has the terminalia dissected and mounted on a transparent card in DMHF (dimeth- ylhydantoin formaldehyde) below the specimen; the abdominal ventrites are glued to the point to the right of the specimen.

Description. Length: male 1.6 mm (1.5–1.8 mm, n = 10); female 2.0 mm (1.9–2.2 mm, n = 10); width: male 0.69 mm (0.62–0.76 mm, n = 10), female 0.91 mm (0.77–0.98 mm, n = 10). Color of cuticle ( Figs. 38–43 ) predominantly dark, gray-black, except light-testaceous on prothorax, clypeolabral region, antennomeres 1–5, basal palpomeres, epipleura, and ill-defined lateroapical crescent of elytra; anterior legs pale except femur slightly infuscate dorsally, middle and hind legs with coxae, tibiae, and tarsi dark, femora pale except sometimes infuscate dorsally ( Figs. 47–49 ). Setation pale, whitish or golden, uniform, conspicuous, decumbent, relatively sparse, not obscuring cuticle color ( Figs. 38, 39, 41, 42 ). Head: Head short, broad, slightly narrower than maximum width of pronotum in female ( Figs. 41, 43 ), about as wide as maximum width of pronotum in male ( Figs. 38, 40 , 53 ); male head ( Figs. 40 , 53 ) 1.48 (1.43–1.52, n = 10), female head ( Fig. 43 ) 1.42 (1.36–1.50, n = 10) times wider than interocular distance; eyes strongly bulging, coarsely faceted. Thorax: Pronotum ( Figs. 41 , 53 ) wider than long, 0.81 (0.76–0.86, n = 20) times as long as wide; widest at middle, lateral edges sinuate. Elytron 3.47 (3.24–3.70, n = 20) times as long as wide ( Figs. 38, 41 ). Legs: Male metatibia ( Fig. 49 ) widest at midlength, narrower in apical and basal halves; male protarsomere 1 ( Fig. 50 ) lobe curved, terminating in three blunt spines; male mesotarsomere 1 ( Fig. 51 ) with a less conspicuous, curved lobe terminating in three blunt spines; male metatarsomere 1 ( Fig. 52 ) with lobe elongate, extending to near apex of tarsomere 2, and terminating in two blunt spines. Abdomen: Male pygidium ( Figs. 38 , 55 ) deeply, broadly excavated apically; female pygidium truncate to slightly emarginate apically ( Fig. 65 ). Male sternite VIII ( Fig. 56 ) apex with broad, relatively shallow medial emargination subtended by a pair of short, triangular lobes; with apical setae nearly uniform between lobes; female sternite VIII ( Fig. 66 ) with a few long setae on each side of emargination, otherwise with short, sparse setae along apical margin. Spiculum gastrale ( Fig. 57 ) with anterior strut about as long as lateral arms. Aedeagus ( Figs. 58, 59 ) with apical third triangular, sides converging to apex; tegmen with median endocarina near base.

Type Specimens Examined. Records reported here are based on the examination of 67 specimens. USA: CALIFORNIA: Imperial County: 9 miles west of Coyote Wells, 26 March 1961, on Hyptis emoryi, Timberlake (paratypes, 1♂, 1♀, UCRC); 7.3 mi. SW of Ocotillo on I-8 West, elev. 525 m., N32°41′38.6′′, W116°5′14.0′′, 16 March 2017, A. J. Mayor, collected beating flowers of Hyptis emoryi (holotype ♂, CAS; paratypes, 2♂♂, 29♀♀, UCRC; 1♂, 1♀, SBMNH); 1.5 mi. E. of Mountain Springs Rd. on I-8 East, elev. 526 m., N32°40′32.7′′, W116°4′26.8′′, 24 March 2017, A. J. Mayor, collected beating flowers of Hyptis emoryi (paratypes, 11♂♂, 13♀♀, UCRC; 2♂♂, 2♀♀, SBMNH [1♂, 1♀, glycerol mounts]); Riverside County: Coyote Creek, 14 April 1963, on Dalea sp. [= Psorothamnus sp. ], E. I. Schlinger (paratype, 1♂, UCRC); 18 miles west of Blythe, 8 April 1963, E. I. Schlinger (paratype, 1♀, UCRC); San Diego County: [Anza] Borrego State Park, 17 March 1957, David Peterson (paratype, 1♀, UCRC).

Other Specimens. USA: CALIFORNIA: San Bernardino County: Mill Creek, San Bernardino Mts. , 6,000 ft, on Arctostaphylos patula , 2 April 1961, Timberlake (1♀, UCRC) . San Diego County: Box Canyon, Anza-Borrego Desert , 19 February 2021 (1♀, on Bugguide: bugguide.net/node/ view/2092390) .

Etymology. The specific epithet is derived from the Latin adjective pygidialis , referring to the highly modified male pygidium in this species.

Host Plant Associations. Adults of G. pygidialis have been collected from flowers of plants in the families Ericaceae , Fabaceae , and Lamiaceae ( Table 1).

Geographic Distribution. Known only from the Colorado Desert of southern California ( Fig. 68 ), and possibly an adjacent canyon in the San Bernardino Mountains (see Remarks).

Seasonal Distribution. 19 February to 14 April ( Fig. 69 ).

Remarks. Gracilivectura pygidialis is easily distinguished from G. mojavensis by the characters given in the Remarks section of the latter species.

The initial collection by AJM of G. pygidialis SW of Ocotillo showed a very skewed sex ratio of four males to 30 females. However, this was an artifact of how quickly the males were flying out of the net, before they could be captured. In a subsequent collection of specimens from “E of Mountain Springs Rd.”, more careful collecting produced a less skewed ratio of 13 males to 16 females.

Pending the collection of males, a single female from Mill Creek in the San Bernardino Mountains collected from Arctostaphylos patula (see above) is tentatively assigned to this species. This is the only specimen of G. pygidialis known from outside the Colorado Desert of California, and we suspect it may be mislabeled.

A. arizonensis G. pygidialis G. mojavensis

30 70 3.5 collected 20 25 collected 60 50 collected 2.5 3 individuals 10 15 individuals 40 20 30... individuals 1.5 2 1 No 5 No 10 No 0.5

0 0 0

JFMAMJJASONDJFMAMJJASONDJFMAMJJASOND

Figures

Figs. 38–43. Gracilivectura pygidialis, new genus and species, habitus (1.5 miles E of Mountain Springs Rd., Imperial Co., CA; SBMNH). Male: 38) Dorsal (inset is dorso-posterior view showing apex of pygidium); 39) Lateral; 40) Frontal. Female: 41) Dorsal; 42) Lateral; 43) Frontal. Scale bars = 1.0 mm.

Figs. 47–52. Gracilivectura pygidialis, new genus and species, anterior view of male right legs and base of tarsus (1.5 miles E of Mountain Springs Rd., Imperial Co., CA; SBMNH). 47) Front leg; 48) Middle leg; 49) Hind leg; 50) Protibial apex and base of protarsus; 51) Mesotibial apex and base of mesotarsus; 52) Metatibial apex and base of metatarsus. Scale bars for 47–49 = 0.5 mm; for 50–52 = 0.1 mm.

Figs. 53–54. Pronota of males of species of Gracilivectura, new genus, dorsal. 53) G. pygidialis, new species; 54) G. mojavensis, new species.

Figs. 55–64. Male terminalia of species of Gracilivectura, new genus. G. pygidialis, new species, holotype: 55) Pygidium; 56) Sternite VIII; 57) Spiculum gastrale; 58) Aedeagus, dorsal; 59) Aedeagus, lateral. G. mojavensis, new species, holotype: 60) Pygidium; 61) Sternite VIII; 62) Spiculum gastrale; 63) Aedeagus, dorsal; 64) Aedeagus, lateral. Scale bars = 0.2 mm.

Figs. 65–67. Gracilivectura pygidialis, new genus and species (1.5 miles E of Mountain Springs Rd., Imperial Co., CA; SBMNH), female terminalia. 65) Pygidium; 66) Sternite VIII; 67) Ovipositor. Scale bars = 0.2 mm.

Fig. 68. Map of distribution of Altovectura arizonensis, new genus and species (triangles), Gracilivectura pygidialis, new genus and species (circles), and G. mojavensis, new species (star).

Fig. 69. Seasonal distribution of Altovectura arizonensis, new genus and species, Gracilivectura pygidialis, new genus and species, and G. mojavensis, new species, based on specimens examined.