Brachymelecta tibialis ( Fabricius, 1793 )

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 : 37-40

Brachymelecta tibialis ( Fabricius, 1793)

Figs 4A , 9B , 16–17

Nomada tibialis Fabricius, 1793: 346 (♂).

Crocisa pantalon Dewitz, 1881: 198 (♂), pl. 5, fig. 2.

Proposed common name

Puerto Rican digger-cuckoo bee.

Diagnosis

The following morphological features in combination can be used to tell B. tibialis apart from all other Brachymelecta except B. haitensis , a Hispaniolan species: the mesoscutum and mesoscutellum both have well-defined bands of pale hairs along the entire midline that connect and thus give the appearance of a single band ( Fig. 16B, D ); the mesoscutellum sometimes also has pale hairs laterally but the pubescence is otherwise dark brown or black, sparse, and does not obscure the underlying integument ( Fig. 16D ); and each mesotibia of the female dorsally has a large glabrous area between a submedial band of offwhite hairs (nearer the base than apex) and a band on the apical margin ( Fig. 16A ). Brachymelecta tibialis may be separated from B. haitensis as follows. Whereas in B. haitensis the T1–T3 apical fasciae are complete (in males) or only narrowly interrupted medially (in females) and the lighter hairs covering the head, mesosoma, and metasoma are pale yellow, in B. tibialis the T1–T3 apical fasciae are narrowly interrupted medially (in males) or widely interrupted medially (in females) and the lighter hairs covering the head, mesosoma, and metasoma are off-white. Brachymelecta tibialis is the easternmost species in its genus and the only one known to occur in Puerto Rico and the U.S. Virgin Islands.

Material examined

Primary type material

COUNTRY UNKNOWN • ♂, N. tibialis holotype; Sehested leg.; NHMD ZMUC 00241576 .

PUERTO RICO • ♂, C. pantalon holotype (studied from images: http://coll.mfn-berlin.de/u/c2e879); Krug leg.; ZMB 22477 for specimen, 22592 for dissected mouthparts .

DNA barcoded material

Unavailable.

Non-barcoded material

COUNTRY UNKNOWN • 1 ♂; “ American Isles ”; Beck leg.; NHMD .

PUERTO RICO • 1 ♀; Aguada, Cerro Gordo ; 23 Aug. 1987; Douglas II leg.; UPRM • 1 ♂; Lares, Lares; 3 Nov. 1922; F. Sein leg.; UPRM Acc. 416-1922 • 1 ♂; Orocovis, Orocovis; 3 Oct. 1979; A.E.Q. leg.; UPRM • 1 ♀; Utuado, Utuado; Jul. 1941; G. Lamboglia leg.; INHS 427051 .

UNITED STATES VIRGIN ISLANDS • 1 ♂; St. Croix ; Eggers leg.; NHMD .

Redescription

Male

MEASUREMENTS. Length 9.4 mm; ITW 2.6 mm; head length 2.7 mm; head width 3.0 mm; fore wing length 8.7 mm.

INTEGUMENT COLORATION. Dark brown to black except as follows. Mandible with apical third golden yellow. Mandible with middle third, labrum, mesoscutellum, metanotum, and legs, excluding dark brown to black coxae and tibial spurs, reddish orange (reddish brown in some non-type specimens). Tegula amber. Fore wing dusky subhyaline throughout except along posterior margin and around third submarginal crossvein and second recurrent vein, where hyaline. Hind wing dusky subhyaline to hyaline. Much of metasoma with reddish tinge.

PUBESCENCE. Face with hairs densest around antennal socket, predominantly off-white/pale yellow but dark brown/gray above antennal socket and in lower paraocular area. Clypeus with upper half densely hairy; lower half nearly bare. Upper paraocular and frontal areas and vertexal area (except along preoccipital ridge and margin of compound eye) mostly exposed. Head with dense, erect hairs along preoccipital ridge off-white except for medial dark brown/gray patch behind ocelli. Genal beard hairs predominantly dark brown/gray. Mesoscutum sparsely hairy except densely hairy anteriorly and along margins, with hairs short, appressed, and predominantly dark brown/gray except for small patch of offwhite hairs on each side along anterior margin between midline and pronotal lobe, pair of central spots of off-white hairs, small patch of off-white hairs in front of axilla, well-defined band of off-white hairs along midline, and off-white hairs along margins.Axilla with conspicuous patch of black hairs. Mesoscutellum with well-defined band of off-white hairs along midline, seemingly continuous with band of pale hairs along midline of mesoscutum, and small patch of off-white hairs laterally but with pubescence otherwise dark brown or black and sparse, not obscuring underlying integument. Metanotum with short, appressed dark brown hairs. Propodeum with erect, predominantly off-white hairs. Mesopleuron sparsely hairy, but with (off-white) hairs moderately dense ventrally as well as between two sparsely hairy circular patches (one beneath base of fore wing around somewhat densely hairy hypoepimeral area, a larger one occupying much of ventrolateral half of mesopleuron). Legs, from coxae to tarsi, with appressed and erect off-white hairs, ventrally with golden-yellow hairs. Profemur with posteroventral fringe of dense, off-white hairs. Protibia with two bands or spots of short, appressed off-white hairs, one in basal half and one on apical margin. Mesotibia with patch of very dense short, appressed off-white hairs, occupying nearly entire dorsal surface. Metatibia with patch of sparser off-white hairs in apical two-thirds. T1–T3 with well-defined, medially interrupted apical fasciae, each with lobe-like anterolateral extension on each side with erect among appressed off-white hairs (that of T2 with pair of anterolateral extensions on each side in C. pantalon holotype and some non-type specimens). T3 with fascia laterally removed from apical margin, narrowed or interrupted mesad each anterolateral extension. T4–T6 without fasciae, although T4 with few sparsely scattered pale hairs present on apical impressed area in some non-type specimens. Exposed metasomal sterna mainly with short, appressed off-white hairs.

SURFACE SCULPTURE. Labrum and clypeus with punctures equally dense (most i≤1d). Small impunctate shiny spot lateral to lateral ocellus. Mesoscutum and mesoscutellum with fine punctures, not much coarser than those of metasomal terga. Mesoscutum and mesoscutellum with punctures equally dense (most i<1d) and similar in size. Mesopleuron with denser (most i<1d) punctures in upper half than ventrolateral half (many i=1–2d), interspaces well-defined and somewhat dull due to tessellate surface microsculpture. Discs of metasomal terga with punctures very fine, dense (i≈1d), interspaces dull due to tessellate surface microsculpture.

STRUCTURE. Mandible tridentate, with small inner tooth approximately ⅓ length of mandible from base and slightly larger inner tooth approximately ⅓ length of mandible from apex as well as usual large apical tooth (rutellum) (difficult to see in N. tibialis holotype because mandibles closed; described from C. pantalon holotype and non-type specimens). Maxillary palpus with one palpomere (mouthparts not extended in N. tibialis holotype; described from two non-type specimens). Scape with greatest length 1.8 × greatest width. F2 nearly as long as wide (L/W ratio = 0.9). Mesoscutellum strongly bigibbous, with pair of long, acute, subparallel spines, directed posteriorly. Lateral surface of propodeum posterior to spiracle with rugose crescent ridge, strongly carinate above and joining anterior lip of spiracle. Fore wing with three submarginal cells. T7 with slight median emargination.

Female

Description as for male except for usual secondary sexual characters and as follows: scape longer, with greatest length 2.2 × greatest width; mesotibia dorsally with large glabrous area between submedial band of off-white hairs (nearer the base than apex) and band on apical margin; T1–T3 with fasciae more widely interrupted medially; T6 with narrow, V-shaped but apically rounded pygidial plate.

Distribution

Previously known only from Puerto Rico and herein newly reported from St. Croix, this is the only species of Brachymelecta known to occur on either of the two islands ( Fig. 4A ).

Ecology

Host records

Unknown. Given that New World Melectini have been associated only with anthophorine bees (mostly Anthophora ), presumably B. tibialis is a cleptoparasite of A. tricolor , the only species in its genus known to occur in Puerto Rico and also the only one represented in the U.S. Virgin Islands ( Brooks 1999).

Floral records

Unknown.

Remarks

Linsley (1943) described the female of Crocisa pantalon (as Melecta (Melectomorpha) pentalon [sic]) based on a specimen from Lares, Puerto Rico (UPRM Acc. 416-1922), which Genaro & Franz (2008) determined was actually a male. Although a female specimen was known to Genaro & Franz (2008), the female of B. tibialis is described here for the first time. Donald B. Baker correctly recognized the holotype of Nomada tibialis as belonging to the same species as “ Nesomelecta pantalon ” (in 1980), and the synonymy was established in Michener (2000) through a personal communication. Moure et al. (2007) erroneously list the USNM and Genaro & Franz (2008) the NHMD (as ZMUC) as the repository for the holotype of C. pantalon . The specimen is actually deposited in the ZMB.

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. 9.Metasoma of male, dorsal view.A. Brachymelecta haitensis (Michener, 1948) (JAG).B. B. tibialis (Fabricius, 1793) (UPRM).

Fig. 16. Brachymelecta tibialis (Fabricius, 1793). A–B, D. Female (INHS 427051). A. Habitus, lateral view. B. Habitus, dorsal view. C. Male (UPRM), habitus, lateral view. D. Axillae and mesoscutellum, dorsal view.

Fig. 17. Fully resolved single most parsimonious tree obtained through maximum parsimony analysis (in TNT) of a combined character set, consisting of 28 morphological characters and DNA barcodes (658 bp, of which 194 were parsimony-informative), with extended implied character weighting. Only morphological characters are shown, with black circles indicating nonhomoplasious changes (autapomorphies or synapomorphies) and empty circles indicating homoplasious changes. Numbers above the circles identify the different characters whereas the numbers below are the assigned character states (see Supp. file 2 for the corresponding descriptions). Numbers to the left of nodes are Bremer support values (above branches) and GC values (below branches).