Brachymelecta larreae ( Cockerell, 1900 )

Onuferko, Thomas M., Packer, Laurence & Genaro, Julio A., 2021, Brachymelecta Linsley, 1939, previously the rarest North American bee genus, was described from an aberrant specimen and is the senior synonym for Xeromelecta Linsley, 1939, European Journal of Taxonomy 754, pp. 1-51 : 34-37

Brachymelecta larreae ( Cockerell, 1900)

Figs 4D , 6E , 14A , 15, 17

Bombomelecta larreae Cockerell, 1900: 361 (♀).

Bombomelecta azygos Viereck, 1903: 181 (♂).

Proposed common name

Creosote digger-cuckoo bee.

Diagnosis

Unique within the genus to B. larreae are each of the following morphological features: the mandibles are bidentate, each with an inner preapical tooth as well as the usual apical tooth (rutellum) ( Fig. 14A ); the mesoscutum does not have any spots or bands of differentiated hairs but is instead covered in dense, uniformly golden-yellow hairs ( Fig. 15A–C ); the mesoscutellum has no spines or well-defined mammiform tubercles, although the mesoscutellum is bigibbous to some degree ( Fig. 15D ); in both sexes the mesotibiae have black hairs only ( Fig. 15A, C ); and T1–T4 lack well-defined fasciae, although ill-defined apical bands of golden-yellow hairs are sometimes present ( Fig. 15A–B ). Brachymelecta larreae is more likely to be confused with some Melecta spp. than other species of Brachymelecta , but in North American Melecta the inner ramus of each tarsal claw is narrow, pointed, and thus resembles the outer ramus and T1 has long, pale hairs, similar in length to those on the dorsum of the mesosoma, whereas in B. larreae the inner ramus of each tarsal claw of the mid- and hind legs is broad, lobe-like, and thus does not resemble the outer ramus (as in all Brachymelecta spp. ) and any pale hairs on T1 (the hairs may be entirely black) are distinctly shorter than those on the dorsum of the mesosoma.

Material examined

Primary type material

USA • ♂, B. azygos holotype; Nevada; ANSP 10128 • ♀, B. larreae holotype; New Mexico, Mesilla Park , Doña Ana County; 9 May 1900; T.D.A. Cockerell leg.; USNM 534229 .

DNA barcoded material

Available, but not BIN-compliant. Specimen examined and sequenced:

USA • 1 ♂; California, Anza-Borrego Desert State Park ; 33.2580° N, 116.4110° W; 26 Feb. 2015; K.J. Hung leg.; BOLD sample ID: CCDB-29918 H07; PCYU SDC.20015 .

Non-barcoded material

USA • 2 ♂♂; California, Apple Valley ; 12 May 1955; W.R. Richards leg.; CNC 891709 , 891711 • 1 ♂; same collection data as for preceding; 20 May 1955; W.R.M. Mason leg.; CNC 899531 • 3 ♀♀, 5 ♂♂; California, Argus Mountains , Inyo County; 22 May 1937; E.C. Van Dyke leg.; CAS • 1 ♂; California, Helendale , San Bernardino County; 16 May 1955; W.R.M. Mason leg.; CNC 891710 • 4 ♀♀; California, Lone Pine , Inyo County; 24 May 1937; E.C. Van Dyke leg.; CAS • 1 ♀; California, Red Mountain ; 16 May 1955; J.E.H. Martin leg.; CNC 891712 • 1 ♀; California, Victorville , San Bernardino County; 20 May 1955; W.R. Richards leg.; CNC 891708 • 1 ♀; Texas, Big Bend National Park (near Chilicotal Mountain); 3 May 1959; J.F. McAlpine leg.; CNC 891716 .

Redescription

Female

MEASUREMENTS. Length 12.3 mm; ITW 3.3 mm; head length 3.4 mm; head width 3.9 mm; fore wing length 11.0 mm.

INTEGUMENT COLORATION. Dark brown to black except as follows. Mandible with apical third golden yellow. Mandible with basal two-thirds, propodeum, legs, excluding black tibial spurs, and much of metasoma with reddish tinge. Fore wing dusky throughout except around third submarginal crossvein and second recurrent vein, where dusky subhyaline. Hind wing dusky subhyaline.

PUBESCENCE. Face with hairs densest around antennal socket, predominantly pale yellow but more extensively black in lower paraocular area and on clypeus. Upper paraocular and frontal areas and vertexal area (except along preoccipital ridge) mostly exposed. Head with dense, erect hairs along preoccipital ridge entirely black except medially where some hairs pale yellow. Genal beard hairs entirely black. Mesoscutum sparsely hairy except densely hairy anteriorly and along margins, with hairs entirely golden yellow. Axilla dorsally with hairs predominantly golden yellow; laterally with hairs predominantly black. Mesoscutellum, metanotum, and much of propodeum (except behind base of hind wing) with erect, predominantly black hairs; hairs otherwise golden yellow. Mesopleuron (except around pronotal lobe where some hairs pale yellow) and metapleuron each covered in sparse, black hairs not obscuring underlying integument. Legs with dark brown to black hairs only. Profemur with posteroventral fringe of dense hairs. Tibiae sparsely hairy. T1 with apical fascia reduced to pair of small patches of golden-yellow tomentum. T2–T4 with ill-defined apical bands of golden-yellow hairs, darker/interrupted medially. Exposed metasomal sterna with short, appressed black hairs.

SURFACE SCULPTURE.Labrum sparsely punctate (many i>2d). Clypeus with punctures more or less equally dense throughout (most i≤1d). Frontal area below median ocellus with impunctate shiny triangular area. Small impunctate shiny spot lateral to lateral ocellus. Mesoscutum and mesoscutellum with coarser punctures than metasomal terga. Mesoscutum and mesoscutellum with punctures equally dense (most i≤1d) and similar in size. Mesopleuron densely punctate (most i≤1d) but with most interspaces welldefined, shining. Discs of metasomal terga with punctures very fine, sparse (most i>1d), interspaces dull due to tessellate surface microsculpture.

STRUCTURE. Mandible bidentate, with small inner tooth approximately ⅖ length of mandible from apex as well as usual large apical tooth (rutellum). Maxillary palpus with five palpomeres. Scape with greatest length 2.3 × greatest width. F2 nearly as long as wide (L/ W ratio = 0.9). Mesoscutellum moderately bigibbous. Lateral surface of propodeum posterior to spiracle relatively flat and unmodified. Fore wing with three submarginal cells. T6 with narrow, V-shaped but apically rounded pygidial plate with median longitudinal ridge.

Male

Description as for female except for usual secondary sexual characters and as follows: head with black hairs only; scape shorter, with greatest length 1.9 × greatest width; F2 shorter, wider than long (L/W ratio = 0.7); mesotibia with patch of very dense short, appressed dark brown to black hairs, occupying nearly entire dorsal surface; T7 with slight median emargination; S4 and S5 each with apical/subapical fringe of dense curved black hairs.

Distribution

Brachymelecta larreae is found in the Chihuahuan, Mojave, and Sonoran deserts of North America ( Fig. 4D ).

Ecology

Host records

Unknown.

Floral records

The holotype of Bombomelecta larreae was collected from the flowers of Larrea tridentata (Sessé & Moc. ex DC.) Coville (Zygophyllaceae) . Linsley (1939) reported this species on Eriodictyon Benth. , Ericameria Nutt. (as Stenotopsis ), and Stanleya Nutt. Floral records from data contributors to Discover Life ( Ascher & Pickering 2020) compiled by J. Pickering are as follows: Dalea , Encelia actonii Elmer , Eriodictyon trichocalyx A. Heller , Eriogonum fasciculatum Benth. , and Hyptis Jacq. (Lamiaceae) . The label of one examined voucher specimen further indicates that this species has been collected from Hyptis emoryi Torr.

Remarks

Linsley (1938) identified the holotype of Bombomelecta azygos as the male of B. larreae and synonymized the former name under the latter. The holotypes of both B. azygos and B. larreae were examined in the present study, and we agree with Linsley’s treatment.

This species exhibits unusual sexual dimorphism in that in females many if not most hairs around the antennal sockets and behind the ocelli are pale yellow, whereas in males the hairs on the head are entirely black. Although in this species the mesoscutellum can be entirely mutic (i.e. without tubercles), in some specimens of B. larreae the mesoscutellum has a pair of very small and thus ill-defined tubercles. Based on known records, adults of B. larreae are active from late February to early June.

Although BIN-compliant sequences are presently not available for B. larreae , a partial sequence, 338 bp in length, is available for a male specimen (BOLD sample ID: CCDB-29918 H07), which was included in the matrix used to construct a phylogeny for Brachymelecta (vide infra).

Figures

Fig. 4. Species distribution maps.A. Brachymelecta alayoi (Michener, 1988) (yellow circles),B. haitensis (Michener, 1948) (red circles), and B. tibialis (Fabricius, 1793) (blue circles). B. B. californica (Cresson, 1878) (red and blue circles indicate barcoded specimens assigned BINs BOLD:AAC6481 and BOLD:AAC6482, respectively). C. B. interrupta (Cresson, 1872). D. B. larreae (Cockerell, 1900). Known localities based on studied material and literature records are indicated by yellow circles except where indicated otherwise; subnational entities colored in orange indicate known/published provincial/ state records.

Fig. 6A–C (continued on next page). Dissected male S7 (left) and S8 (right), ventral view (with anterior ends oriented toward the top). A. Brachymelecta californica (Cresson, 1878) (photo of Melecta californica paralectotype (ANSP 2292-5)).B. B. californica (photo ofM.? mucida holotype (ANSP 2294) (herein synonymized under B. californica)) (S8 appears to have been damaged/split anteromedially). C. B. haitensis (Michener, 1948) (JAG).

Fig. 14. Mandibles of female. A. Brachymelecta larreae (Cockerell, 1900) (CNC 891712), each mandible has a single inner (preapical/almost submedial) tooth (blue arrow). B. B. interrupta (Cresson, 1872) (CNC 891714), each mandible has both an inner basal tooth as well as an inner preapical (almost submedial) tooth (blue arrows).

Fig. 15. Brachymelecta larreae (Cockerell, 1900). A, D. Female (CNC 891708). A. Habitus, lateral view. B. Female (CNC 891716), habitus, dorsal view. C. Male (CNC 899531), habitus, lateral view. D. Axillae and mesoscutellum, dorsal view.