Brachymelecta interrupta ( Cresson, 1872 )

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 : 30-33

Brachymelecta interrupta ( Cresson, 1872)

Figs 4C , 6D , 13, 14B , 17

Melecta interrupta Cresson, 1872: 275 (♀, ♂); Cresson, 1916: 121 (♀) (lectotype designation). Melecta interrupta var. fallugiae Cockerell, 1904: 23 (♀).

Melecta interrupta var. rociadensis Cockerell, 1904: 23 (♂).

Proposed common name

Interrupted digger-cuckoo bee.

Diagnosis

The following morphological features in combination can be used to tell B. interrupta apart from all other Brachymelecta : the mesoscutum has a pair of anterior spots or (paramedian) bands of hairs darker than the surrounding yellow-orange hairs ( Fig. 13B ); the mesoscutellum has a pair of short, mammiform tubercles ( Fig. 13D ); the fore wings are infuscate throughout except around the third submarginal crossvein and second recurrent vein, where they are subhyaline ( Fig. 13A–C ); and T3 and T4 each have a medially interrupted fascia that is broadened anterolaterally, that of T3 into the inner pair of anterolateral extensions (there are two such lobe-like extensions on each side) ( Fig. 13A–C ). Brachymelecta interrupta is most similar to B. californica , but in B. californica the fore wings are infuscate apically, with most cells as well as the membrane around the third submarginal crossvein and second recurrent vein subhyaline, and T3 and T4 each have a medially interrupted fascia that is narrowed or interrupted (as opposed to continuously expanded) laterally, mesad the inner pair of anterolateral extensions. Additionally, in B. californica the lighter hairs covering the head, mesosoma, and metasoma are off-white or very rarely pale yellow, whereas in B. interrupta they range from pale yellow to yellow orange.

Material examined

Primary type material

USA • ♀, M. interrupta var. fallugiae holotype; New Mexico, Pecos; 27 Jun.; M. Grabham leg.; CAS 4672 • ♂, M. interrupta var. rociadensis holotype; New Mexico, Rociada , San Miguel County; 10 Aug.; T.D.A. Cockerell leg.; USNM 534231 • ♀, M. interrupta lectotype; Texas; ANSP 2291 .

DNA barcoded material

Available. BIN: BOLD:ABU5955. Specimens examined and sequenced:

USA • 1 ♀; Arizona, Southwestern Research Station (5 mi W of Portal), Cochise County; 28 Aug. 2007; H.T. Ngo leg.; BOLD sample ID: CCDB-34570 B06; PCYU • 1 ♀; Arizona, Southwestern Research Station (5 mi W of Portal), Cochise County; 31.8840° N, 109.2060° W; 31 Aug. 2011; N. de Silva leg.; BOLD sample ID: 14511H06-AZ; PCYU 0003840 • 1 ♀; New Mexico, 10 mi N of Mimbres, Grant County; 32.9778° N, 108.0528° W; 6 Aug. 2007; M. Buck leg.; BOLD sample ID: CCDB-34570 B04; DEBU debu00291180 .

Non-barcoded material

USA • 1 ♀; Arizona, Canelo , Santa Cruz County; 27 Jun. 1965; R.F. Sternitzky leg.; CNC 891717 • 1 ♂; same collection data as for preceding; CNC 891718 • 1 ♀; Arizona, Southwestern Research Station (5 mi W of Portal), Cochise County; 26 Aug. 2007; H.T. Ngo; PCYU • 5 ♀♀, 1 ♂; Colorado; ANSP • 1 ♀; Colorado, Logan County; 40.4894° N, 102.7412° W; 31 May 2012; M. Vandever et al. leg.; CSUC • 1 ♂; Illinois; ANSP • 1 ♀; Kansas, Wallace , Wallace County; Jul. 1885; CNC 891738 • 1 ♂; same collection data as for preceding; CNC 891737 • 1 ♀; Mississippi, Lafayette County; Sep.–Oct.1956; E.R. Wall leg.; CNC 891699 • 1 ♀; Missouri, Lake Ozark ; 20 Sep. 1939; E.C. Van Dyke leg.; CAS • 2 ♀♀, 2 ♂♂; Nebraska; ANSP • 1 ♀; New Mexico, 1 mi E of top of pass, near Sierra Blanca, Hwy 70; 27 Aug. 1962; F.M. Hull leg.; CNC 891735 • 1 ♀; New Mexico, Manzano Mountains (8 mi W of Manzano, near New Canyon Campground), Torrance County; 28 Aug. 1993; J.E. O’Hara leg.; CNC 891714 • 1 ♀ (labelled as “ Melecta interrupta Cress. ♀ TYPE” but probably a non-type specimen); Texas; USNM 534230 • 1 ♂; Texas, The Rockpile (30 mi NW of Fort Davis); 28 May 1959; J.F. McAlpine leg.; CNC 891719 .

Redescription

Female

MEASUREMENTS. Length 12.7 mm; ITW 2.9 mm; head length 3.4 mm; head width 4.0 mm; fore wing length 11.7 mm.

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

PUBESCENCE. Face with hairs densest around antennal socket, predominantly pale yellow to yellow orange but almost entirely 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 yellow orange except for pair of black patches, each behind lateral ocellus and in front of paramedian band (hairs somewhat faded in M. interrupta lectotype; described from nontype specimens). Genal beard hairs almost entirely black. Mesoscutum sparsely hairy except densely hairy anteriorly, narrowly along lateral margin, and in space between parapsidal line and axilla, with hairs predominantly yellow orange except for black paramedian band. Axilla with conspicuous patch of black hairs. Mesoscutellum and much of lateral surface of propodeum (except near bases of mesocoxa and metacoxa) with erect, predominantly yellow-orange hairs. Metanotum and propodeal triangle with erect, predominantly black hairs. Mesopleuron and metapleuron each with upper half covered in dense, yellow-orange hairs greatly obscuring underlying integument and lower half covered in sparser, black hairs not obscuring underlying integument. Legs, from coxae to tarsi, with patches of appressed and erect pale yellow to yellow-orange hairs among more numerous dark brown to black hairs. Profemur with posteroventral fringe of dense, predominantly pale yellow hairs. Tibiae each with small, inconspicuous spot of short, appressed pale yellow hairs in basal half (in some non-type specimens, protibia and metatibia each with additional patch of short, appressed pale yellow hairs on apical margin). T1–T5 with well-defined medially interrupted apical fasciae, laterally with erect among appressed yellow-orange hairs. T2 and T3 fasciae each with pair of lobe-like anterolateral extensions on each side. T3–T5 each with fascia broadened anterolaterally, that of T3 into inner pair of anterolateral extensions. 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) except for small impunctate shiny spot medially on lower margin. Small impunctate shiny spot lateral to lateral ocellus, another behind median ocellus. Mesoscutum and mesoscutellum with coarser punctures than metasomal terga. Mesoscutum densely punctate (most i≤1d) except for small impunctate shiny spot between paramedian band and parapsidal line and along posterior margin around midline, where more sparsely punctate (few i>1d). Mesoscutellum with punctures more or less equally dense throughout (most i≤1d) and similar in size to those of mesoscutum. Mesopleuron densely punctate (most i<1d) but with most interspaces well-defined, shining. Discs of metasomal terga with punctures very fine, sparse (most i>1d), interspaces dull due to tessellate surface microsculpture.

STRUCTURE. Mandible tridentate, with small inner tooth approximately ⅓ length of mandible from base and larger inner tooth approximately ⅖ length of mandible from apex as well as usual large apical tooth (rutellum) (difficult to see in M. interrupta lectotype because mandibles closed; described from non-type specimens). Maxillary palpus with five palpomeres (mouthparts not extended in M. interrupta lectotype; described from non-type specimen). Scape with greatest length 2.3 × greatest width. F2 nearly as long as wide (L/ W ratio = 0.9). Mesoscutellum moderately bigibbous, with pair of short, conical mammiform tubercles. 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: scape shorter, with greatest length 1.8 × greatest width; F2 shorter, wider than long (L/W ratio = 0.7); mesotibia with patch of very dense short, appressed yellow-orange 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 interrupta is the second-most widely distributed member of its genus, after B. californica . Its range includes much of the Central United States, parts of the Southwestern United States (as far west as eastern Arizona), and north-central Mexico ( Fig. 4C ).

Ecology

Host records

According to Mitchell (1962), the host of B. interrupta is Anthophora abrupta , but no details were provided with regard to the basis of this apparent association. That a different species, A. walshii Cresson, 1869 , is the primary if not only host of B. interrupta is strongly suggested by three separate observations of the latter in the presence/vicinity of the former (by Robertson 1926; Graenicher 1935; Bouseman 1982) and there being much greater range overlap (see Ascher & Pickering 2020) between B. interrupta and A. walshii (both are widespread from the Midwestern United States to Western North America) than between B. interrupta and A. abrupta (an eastern species).

Floral records

The holotype of Melecta interrupta var. fallugiae was collected from the flowers of Fallugia Endl. (Rosaceae) . Robertson (1929) reported B. interrupta (as M. interrupta ) on Coreopsis palmata Nutt. and Pycnanthemum flexuosum (Walter) Britton, Sterns & Poggenb. (Lamiaceae) . Linsley (1939) reported this species on Cleome L. ( Cleomaceae ), Dalea L. ( Fabaceae ) (as Petalostemon ), and Monarda L. ( Lamiaceae ), Hurd (1953) on Baccharis L., Hurd et al. (1980) on Helianthus annuus , and Bouseman (1982) on H. pauciflorus Nutt. (as H. rigidus ) and Rudbeckia hirta L. ( Asteraceae ). Discover Life ( Ascher & Pickering 2020) cites the following floral record contributed by the Bee Biology and Systematics Laboratory: Cirsium Mill. Images on BugGuide (https://bugguide.net) show this species visiting Dalea candida Willd. The label of one examined voucher specimen further indicates that this species has been collected from Marrubium vulgare L.

Remarks

Brachymelecta interrupta was described (as Melecta interrupta ) from two specimens (one female and one male), from Dallas and Comal Counties (Texas), although it is not clear from the description or the female specimen’s labels which locality corresponds to which specimen. We have not seen the male specimen, deposited in the Museum of Comparative Zoology (MCZ) in Cambridge, MA, USA, but according to Cockerell (1907) it is from Dallas, so presumably the female is from Comal County. Cresson (1916) designated the female specimen, deposited in the ANSP (catalog number: 2291), as the lectotype of Melecta interrupta . Confusingly, there is also a female specimen in the primary type collection of the USNM (catalog number: 534230) bearing the label “ Melecta interrupta Cress. ♀ TYPE”. This specimen (also from Texas) bears another label that says “Type No 1764 U.S. N.M” and is listed as the lectotype of M. interrupta in the Department of Entomology Collections database (https://collections.nmnh.si.edu/search/ento/). It is not clear when or if this designation was published or which of the two females constituted the basis for the original description, but given that Cresson (1916), who described the species, designated the specimen at the ANSP as the lectotype, it is herein regarded as such as well (with the male at the MCZ, labelled as a syntype, recognized as the lectoallotype).

Cockerell (1904) described two “varieties” of M. interrupta (both from New Mexico) on the basis that neither precisely agrees with the “typical form from Texas ”. In Linsley (1939), M. var. fallugiae appears in the synonymy list for M. interrupta , although it is referred to as a variety rather than a synonym of M. interrupta , one in which the pale pubescence is more orange than yellow. Mitchell (1962) apparently accepted this as a junior synonym of X. interrupta , and we agree with Mitchell’s treatment. In the holotype of M. interrupta var. fallugiae , the pale pubescence is the same yellow-orange color exhibited by the lectotype of M. interrupta .

Linsley (1939) regarded the other variety ( M. var. rociadensis ) as a separate species ( M. rociadensis ) from M. interrupta ; however, later Hurd & Linsley (1951) indicated that they were unable to reliably distinguish M. var. rociadensis from M. interrupta and therefore synonymized the former name under the latter. Aside from the paler pubescence exhibited by the M. var. rociadensis holotype, its description applies equally well to the lectotype of M. interrupta . Cockerell’s (1904) description, rather than differentiating the M. var. rociadensis holotype from the “typical form” of M. interrupta , instead lists the features (the dark tegulae and wings and unique metasomal markings) that separate M. var. rociadensis from M. miranda (now a junior synonym of B. californica ). These differences, however, can be used to separate any representatives of B. interrupta (including the lectotype of M. interrupta ) from the holotype of M. miranda . Although the pale hairs in B. interrupta range from pale yellow to yellow orange, the variation is continuous and the differences in hair color do not correspond to any geographic pattern. Hence, we agree with the treatment of Hurd & Linsley (1951) and do not regard M. var. rociadensis as a valid taxon.

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. 13. Brachymelecta interrupta (Cresson, 1872). A. Female (CNC 891735), habitus, lateral view. B. Melecta interrupta lectotype, ♀ (ANSP 2291), habitus, dorsal view. C. Male (CNC 891719), habitus, lateral view. D. Female (BOLD sample ID: 14511H06-AZ; PCYU 0003840), axillae and mesoscutellum, dorsal view (blue arrow indicates one of two short, mammiform tubercles of mesoscutellum).