Sphecodes
Sphecodes is a genus of cuckoo bees from the family Halictidae, the majority of which are black and red in colour and are colloquially known as blood bees. Sphecodes bees are kleptoparasitic on ground-nesting bees, especially bees in the genera Lasioglossum, Halictus and Andrena. The adults consume nectar, but because they use other bees' provisions to feed their offspring they do not collect pollen.
Distribution
Sphecodes is a cosmopolitan genus with species represented on every continent except Antarctica. The genus is also very species rich, with 21 species described from Siberia, 33 species from Central Europe, 17 species from the Indian region, 26 from the Arabian Peninsula and surrounding region, and 21 from Southeast Asia. In the Americas, there are 11 species described from the Neotropics and 63 from the Nearctic. Australia has only two native species, S. manskii and S. profugus, both of which are restricted to the northeast. The species Sphecodes albilabris is thought to have been introduced to both Australia and the United States by accident.
Taxonomy
The genus was erected in 1804 by Pierre Latreille for the species Sphecodes gibbus. That species was initially described by Carl Linnaeus as Sphex gibba. The fact that the type specimen was initially described as a wasp was not lost on Latreille as the name he chose for the genus, Sphecodes, means "like a wasp". In the late 18th and early 19th-centuries, the taxonomy of Apoidea was very unclear, and at various points Sphecodes species were described as the following genera: Sphex Linnaeus, 1758; Nomada Latrielle, 1802; Halictus Latrielle, 1804; Apis Linnaeus, 1758; Melitta Kirby, 1802; Andrena Fabricius, 1775; and Tiphia Fabricius, 1775.
The following genera are now considered synonyms of Sphecodes: Dichroa Illiger, 1806; Sabulicola Verhoeff 1890; Thrausmus Buysson 1900; Dialonia Robertson, 1903; Machaeris Robertson, 1903; Stelidium Robertson, 1903; and Sphegodes Mavromoustakis, 1949.
Charles Robertson was particularly prolific in describing genera that would be synonomized with Sphecodes later on, although the differences he noticed are now reflected in the subgenera. The following genera are now considered subgenera: Drepanium Robertson, 1903; Proteraner Robertson, 1903; and Sphecodium Robertson, 1903. Subgeneric classifications are currently debated, and whether they are truly monophyletic groups remains unknown.
Callosphecodes Friese, 1909 may either be a synonym or subgenus, but specimens that match its description are exceedingly rare.
Phylogeny
Relatively few phylogenetic studies have been completed for the genus, and none that are exhaustive or analyze biogeography. Sphecodes is a member of the family Halictidae and in the tribe Sphecodini. Sphecodini is sister to Halictini sensu stricto. Genus-level relationships within Sphecodini are still being determined, but recent phylogenies suggest that Sphecodes is sister to the genus Eupetersia. It is unknown exactly how many species there are worldwide, and even well-studied regions of the world such as the United States and Europe likely have many species to be described or synonymized.
A note on Halictinae tribes
There are two diverging approaches to tribe-level phylogenies within Halictinae. The first, used by taxonomists like Danforth, Gibbs, and Brady recognizes five distinct tribes: Augochlorini, Thrinchostomini, Caenohalictini, Halictini sensu stricto, and Sphecodini. This is also the approach that Wikipedia uses. The second, used by Ascher, Michener, Straka, and Engel among others recognizes only two: Augochlorini and Halictini sensu lato, with the rest of the tribes relegated to subtribes within Halictini s. l. This approach is also used by resources such as iNaturalist and BugGuide. Both are valid and represent the same evolutionary relationships.
Morphology
Sphecodes is in the family Halictidae, a group distinguished from other bee families by a highly arcuate basal vein. In North America, Sphecodes is the only genus of Sphecodini present.
Sphecodes are small-to-medium bees, usually with distinctive red abdomens although males are sometimes entirely black. The genus has somewhat oval, brachycephalic heads and thicker antennae compared to other bees. Most species have three submarginal cells, but some consistently have two, and others have either two or three. Their body size is correlated with that of their host: large Sphecodes parasitize larger hosts like Andrena, while small Sphecodes are more often associated with small hosts like Perdita. Like other kleptoparasitic bees, they are largely hairless and females lack scopae on their hind tibia. Both sexes have thickened and highly rugose cuticles. This adaptation allows them to deflect and block stings when fighting their hosts. In many other cuckoo bee genera, the larvae sport large mandibles used to kill the host. These are absent in the young of Sphecodes, where it is the adult that dispatches the host egg or larva.
Identification of these bees is difficult, in part due to lack of research and published keys. Important characters include the antennae, mandibles, propodeum, and male genitalia.
Natural history
Sphecodes are most commonly found hovering over the nest sites of their host bees. Females will either kill the hosts or wait until the nests are unguarded. She will then enter the nest, laying her own egg on the pollen provisions and killing the egg or larvae of the host. The larval bee will feed on the pollen provisions throughout the winter, emerging as adults in the spring or fall. Their phenology does not necessarily overlap with that of their host, making host associations sometimes difficult to determine.
There are few studies of parasitism within Sphecodes and much of what we know is inferred from a small number of observations. Due to the range of sociality of its hosts, particularly Halictus and Lasioglossum, Sphecodes species display a broad range of parasitism tactics.
For solitary hosts or social hosts in a solitary phase of their lifecycle, the female Sphecodes will wait until the host leaves. Then, she will enter the nest undetected, laying her eggs in recently closed nest cells. If the host bee comes back, the Sphecodes will fight with her, typically killing or parasitizing the host. Other cuckoo bee genera such as Nomada also sneak into unguarded nests, chemically mimicking their Andrena hosts to remain undetected. Surprisingly, studies of the cuticular hydrocarbons and Dufour's gland secretions suggest that Sphecodes do not mimic their host.
If the hosts are either communal or eusocial and thus always have some bees guarding their nests, Sphecodes will deploy a different tactic. In this scenario, the female Sphecodes drives the host out of the nest, possibly chemically. Augochlora have been reported leaving disoriented, or in quick flight.
Some species will also deploy a much more aggressive response, battling and killing every member of the colony. She will then spend several hours laying eggs in the provisioned brood cells. The propensity for Sphecodes to kill the adult hosts is unusual in kleptoparasitic bees, although they prefer to enter unguarded nests.
Hosts
Sphecodes species are most frequently associated with the closely related genera Lasioglossum and Halictus. However, they have also been known to parasitize Perdita, Andrena, Calliopsis, Augochlorella, Melitturga, Colletes, Agapostemon, and possibly Augochloropsis. Host associations of most Sphecodes species, particularly outside of Europe, are largely unknown.
Some species parasitize a wide range of hosts, while others are species or genus-specific. Within a generalist species, however, studies have shown that individual bees are typically specialists: a single female Sphecodes will visit the nests of a single host species, although other individuals of the same species of Sphecodes may use different hosts.
Host switching is widespread in the evolution of Sphecodes, with one paper finding it has evolved at least 17 times. This flexibility could be due to their destructive modes of parasitism or the high degree of host generalism.
Species
There are over 300 known species in the genus Sphecodes. As of 2015, there were 319 valid species described. The following list may be incomplete and does not reflect recent synonomies.Sphecodes abuensis Nurse, 1903Sphecodes abyssinicus Sichel, 1865Sphecodes aeneiceps Friese, 1917Sphecodes aino Tsuneki, 1983Sphecodes akitanus Tsuneki, 1983Sphecodes albifrons Smith, 1879Sphecodes albilabris Sphecodes albociliatus Meyer, 1922Sphecodes algoensis Blüthgen, 1928Sphecodes alternatus Smith, 1853Sphecodes amakusensis Yasumatsu & Hirashima, 1951Sphecodes anatolicus Warncke, 1992Sphecodes andinus Schrottky, 1906Sphecodes angarensis Cockerell, 1937Sphecodes anonymus Blüthgen, 1928Sphecodes antennariae Robertson, 1891Sphecodes apicatus Smith, 1853Sphecodes arequipae Meyer, 1925Sphecodes argentinus Schrottky, 1906Sphecodes armeniacus Warncke, 1992Sphecodes arnoldi Blüthgen, 1928Sphecodes aroniae Mitchell, 1960Sphecodes arroyanus Cockerell, 1904Sphecodes arvensiformis Cockerell, 1904Sphecodes asclepiadis Cockerell, 1898Sphecodes aspericollis Sichel, 1865Sphecodes assamensis Blüthgen, 1927Sphecodes atlanticus Warncke, 1992Sphecodes atlantis Mitchell, 1956Sphecodes atriapicatus Strand, 1912Sphecodes autumnalis Mitchell, 1956Sphecodes awaensis Tsuneki, 1983Sphecodes bakeri Cockerell, 1915Sphecodes banaszaki Nobile & Turrisi, 2004Sphecodes banksii Lovell, 1909Sphecodes baratonis Tsuneki, 1983Sphecodes barbatus Blüthgen, 1923Sphecodes basalis Sichel, 1865Sphecodes binghami Blüthgen, 1924Sphecodes biroi Friese, 1909Sphecodes bischoffi Meyer, 1925Sphecodes bogotensis Meyer, 1922Sphecodes bonaerensis Holmberg, 1886Sphecodes borealis Cockerell, 1937Sphecodes brachycephalus Mitchell, 1956Sphecodes brasiliensis Schrottky, 1910Sphecodes braunsi Blüthgen, 1928Sphecodes breviclypeatus Tsuneki, 1984Sphecodes bruchi Schrottky, 1906Sphecodes brunneipes Friese, 1914Sphecodes californicus Meyer, 1922Sphecodes campadellii Nobile & Turrisi, 2004Sphecodes candidus Meyer, 1925Sphecodes capensis Cameron, 1905Sphecodes capriciosus Schrottky, 1906Sphecodes capverdensis Pauly & LaRoche, 2002Sphecodes carolinus Mitchell, 1956Sphecodes castaneae Mitchell, 1960Sphecodes centralis Cockerell, 1938Sphecodes cephalotes Meyer, 1920Sphecodes chaprensis Blüthgen, 1927Sphecodes chibaensis Tsuneki, 1984Sphecodes chichibuensis Tsuneki, 1986Sphecodes chichibuus Tsuneki, 1986Sphecodes chilensis Spinola, 1851Sphecodes clematidis Robertson, 1897Sphecodes clypeatus Friese, 1917Sphecodes columbiae Cockerell, 1906Sphecodes combai Nobile & Turrisi, 2004Sphecodes confertus Say, 1837Sphecodes confusus Blüthgen, 1928Sphecodes congoensis Sphecodes connexus Blüthgen, 1928Sphecodes convergens Michener, 1978Sphecodes convergens Tsuneki, 1983Sphecodes coptis Tsuneki, 1983Sphecodes cordillerensis Jörgensen, 1912Sphecodes cordovensis Sphecodes coriae Moure & Hurd, 1987Sphecodes coronus Mitchell, 1956Sphecodes costaricensis Friese, 1917Sphecodes crassanus Warncke, 1992Sphecodes crassicornis Smith, 1879Sphecodes crassus Thomson, 1870Sphecodes crawfordi Mitchell, 1956Sphecodes cressonii Sphecodes cristatus Hagens, 1882Sphecodes croaticus Meyer, 1922Sphecodes daishi Tsuneki, 1983Sphecodes dathei Schwarz, 2010Sphecodes davisii Robertson, 1897Sphecodes decorus Sphecodes dichrous Smith, 1853Sphecodes dilutus Cockerell, 1936Sphecodes diremptus Cockerell, 1932Sphecodes discoverlifei Astafurova & Proshchalykin, 2020Sphecodes distinctus Meyer, 1925Sphecodes duplex Blüthgen, 1927Sphecodes duplipunctatus Tsuneki, 1983Sphecodes dusmeti Blüthgen, 1924Sphecodes dyozankeanus Tsuneki, 1983Sphecodes engeli Astafurova & Proshchalykin, 2020Sphecodes ephippius Sphecodes equator Vachal, 1904Sphecodes eritrinus Friese, 1915Sphecodes eugnathus Blüthgen, 1928Sphecodes eustictus Cockerell, 1906Sphecodes exaltus Mitchell, 1956Sphecodes fattigi Mitchell, 1956Sphecodes ferruginatus Hagens, 1882Sphecodes fimbriatus Blüthgen, 1928Sphecodes formosus Cockerell, 1911Sphecodes fortior Cockerell, 1898Sphecodes fragariae Cockerell, 1903Sphecodes friesei Herbst, 1908Sphecodes fudzi Tsuneki, 1983Sphecodes fuelleborni Blüthgen, 1928Sphecodes fukuiensis Tsuneki, 1983Sphecodes fumipennis Smith, 1853Sphecodes galeritus Blüthgen, 1927Sphecodes galerus Lovell & Cockerell, 1907Sphecodes genaroi Engel, 2006Sphecodes geoffrellus Sphecodes gibbus Sphecodes grahami Cockerell, 1922Sphecodes grandidieri Sphecodes granulosus Sichel, 1865Sphecodes guineensis Vachal, 1903Sphecodes hagensi Ritsema, 1880Sphecodes haladai Warncke, 1992Sphecodes hanedai Tsuneki, 1983Sphecodes hasshanus Tsuneki, 1983Sphecodes hemirhodurus Cockerell, 1921Sphecodes heraclei Robertson, 1897Sphecodes hesperellus Cockerell, 1904Sphecodes hirtellus Blüthgen, 1923Sphecodes howardi Cockerell, 1922Sphecodes hudsoni Cockerell, 1913Sphecodes hyalinatus Hagens, 1882Sphecodes hydrangeae Mitchell, 1956Sphecodes illinoensis Sphecodes ilyadadaria Astafurova & Proshchalykin, 2020Sphecodes indicus Bingham, 1898Sphecodes invidus Sphecodes inornatus Sphecodes insularis Smith, 1858Sphecodes intermedius Blüthgen, 1923Sphecodes iosephi Nobile & Turrisi, 2004Sphecodes iridescens Cockerell, 1921Sphecodes iridipennis Smith, 1879Sphecodes itidyo Tsuneki, 1983Sphecodes ituriensis Blüthgen, 1928Sphecodes iwatensis Tsuneki, 1983Sphecodes izumindus Tsuneki, 1986Sphecodes japonicus Cockerell, 1911Sphecodes javanicus Friese, 1914Sphecodes joergenseni Meyer, 1920Sphecodes johnsonii Lovell, 1909Sphecodes kaisensis Tsuneki, 1983Sphecodes kamafuse Tsuneki, 1983Sphecodes kershawi Perkins, 1921Sphecodes kincaidii Cockerell, 1898Sphecodes kisukei Tsuneki, 1983Sphecodes kitamius Tsuneki, 1983Sphecodes knetschi Cockerell, 1898Sphecodes koikensis Tsuneki, 1983Sphecodes kristenseni Meyer, 1919Sphecodes laetus Meyer, 1922Sphecodes lasimensis Blüthgen, 1927Sphecodes laticaudatus Tsuneki, 1983Sphecodes laticeps Meyer, 1920Sphecodes latifrons Cockerell, 1919Sphecodes lautipennis Cockerell, 1908Sphecodes levicinctus Cockerell, 1936Sphecodes levis Lovell & Cockerell, 1907Sphecodes libericus Cockerell, 1936Sphecodes longuloides Blüthgen, 1923Sphecodes longulus Hagens, 1882Sphecodes lunaris Vachal, 1904Sphecodes luteiventris Friese, 1925Sphecodes luzonicus Blüthgen, 1925Sphecodes macswaini Michener, 1954Sphecodes maetai Tsuneki, 1984Sphecodes magnipunctatus Sphecodes majalis Pérez, 1903Sphecodes malayensis Blüthgen, 1927Sphecodes manchurianus Strand & Yasumatsu, 1938Sphecodes mandibularis Cresson, 1872Sphecodes manni Cockerell, 1913Sphecodes manskii Sphecodes marcellinoi Nobile & Turrisi, 2004Sphecodes marginatus Hagens, 1882Sphecodes maruyamanus Tsuneki, 1983Sphecodes melanopus Schrottky, 1906Sphecodes mendocinus Jörgensen, 1912Sphecodes metanotiaeus Sichel, 1865Sphecodes metathoracicus Sichel, 1865Sphecodes mexicanorum Cockerell, 1919Sphecodes millsi Cockerell, 1919Sphecodes minarum Schrottky, 1910Sphecodes miniatus Hagens, 1882Sphecodes minor Robertson, 1898Sphecodes monilicornis Sphecodes montanus Smith, 1879Sphecodes murotai Tsuneki, 1983Sphecodes mutillaeformis Schrottky, 1906Sphecodes mutsu Tsuneki, 1983Sphecodes mutsuoides Tsuneki, 1984Sphecodes nambui Tsuneki, 1983Sphecodes natalensis Friese, 1925Sphecodes niger Hagens, 1874Sphecodes nigeriae Blüthgen, 1928Sphecodes nigricans Timberlake, 1940Sphecodes nigricorpus Mitchell, 1956Sphecodes nigritus Ashmead, 1900Sphecodes nippon Meyer, 1922Sphecodes nipponicus Yasumatsu & Hirashima, 1951Sphecodes nitidissimus Cockerell, 1910Sphecodes niveatus Meyer, 1925Sphecodes niveipennis Meyer, 1925Sphecodes nomioidis Pesenko, 1979Sphecodes nyassanus Strand, 1911Sphecodes ohdeyamanus Tsuneki, 1984Sphecodes ohtsukius Tsuneki, 1984Sphecodes okuyetsu Tsuneki, 1983Sphecodes olivieri Lepeletier, 1825Sphecodes olympicus Cockerell, 1904Sphecodes oneili Cameron, 1905Sphecodes oriundus Vachal, 1903Sphecodes pallitarsis Vachal, 1909Sphecodes paraguayensis Schrottky, 1906Sphecodes paraplesius Lovell, 1911Sphecodes patagonicus Schrottky, 1906Sphecodes patruelis Cockerell, 1913Sphecodes pecosensis Cockerell, 1904Sphecodes pectoralis Morawitz, 1876Sphecodes pellucidus Smith, 1845Sphecodes perlustrans Cockerell, 1898Sphecodes perplexus Nurse, 1903Sphecodes persimilis Lovell & Cockerell, 1907Sphecodes peruensis Meyer, 1925Sphecodes pieli Cockerell, 1931Sphecodes pilosulus Smith, 1879Sphecodes pimpinellae Robertson, 1900Sphecodes pinguiculus Pérez, 1903Sphecodes politulus Cockerell, 1937Sphecodes profugus Cockerell, 1910Sphecodes propinquus Blüthgen, 1928Sphecodes prosphorus Lovell & Cockerell, 1907Sphecodes prostygius Mitchell, 1960Sphecodes pseudocrassus Blüthgen, 1924Sphecodes pseudofasciatus Blüthgen, 1925Sphecodes pseudoredivivus Astafurova & Proshchalykin, 2020Sphecodes pulsatillae Cockerell, 1906Sphecodes punctatus Sichel, 1865Sphecodes puncticeps Thomson, 1870Sphecodes puncticollis Sichel, 1865Sphecodes punctiscutum Eardley & R. P. Urban, 2006Sphecodes pusillus Cockerell, 1937Sphecodes pycnanthemi Robertson, 1897Sphecodes quadrimaculatus Blüthgen, 1928Sphecodes quellensis Blüthgen, 1927Sphecodes ralunensis Friese, 1909Sphecodes ranunculi Robertson, 1897Sphecodes redivivus Blüthgen, 1927Sphecodes reticulatus Thomson, 1870Sphecodes rhois Sphecodes rikuchu Tsuneki, 1983Sphecodes rohweri Cockerell, 1907Sphecodes rotundiceps Cockerell, 1919Sphecodes rubicundus Hagens, 1875Sphecodes rubripes Spinola, 1838Sphecodes rudiusculus Sphecodes rufichelis Strand, 1912Sphecodes ruficrus Sphecodes rufiscapis Vachal, 1909Sphecodes rufithorax Morawitz, 1876Sphecodes rufiventris Sphecodes rufoantennatus Benoist, 1950Sphecodes rugulosus Sichel, 1865Sphecodes samarensis Blüthgen, 1927Sphecodes sapporensis Tsuneki, 1983Sphecodes sauteri Meyer, 1925Sphecodes saxicolus Warncke, 1992Sphecodes scabricollis Wesmael, 1835Sphecodes schenckii Hagens, 1882Sphecodes schoanus Blüthgen, 1928Sphecodes schwarzi Astafurova & Proshchalykin, 2015Sphecodes scrobiculatus Pauly & Brooks, 2001Sphecodes semicoloratus Sphecodes senegalensis Sichel, 1865Sphecodes shawi Lovell, 1911Sphecodes shillongensis Blüthgen, 1927Sphecodes shirozui Tsuneki, 1983Sphecodes sibuyanensis Cockerell, 1925Sphecodes sikkimensis Blüthgen, 1927Sphecodes silvicola Tsuneki, 1983Sphecodes simillimus Smith, 1873Sphecodes simlaensis Blüthgen, 1924Sphecodes smilacinae Robertson, 1897Sphecodes solidaginis Cockerell, 1937Sphecodes solonis Graenicher, 1911Sphecodes sophiae Cockerell, 1898Sphecodes spinulosus Hagens, 1875Sphecodes strandi Meyer, 1920Sphecodes stygius Robertson, 1893Sphecodes subconfertus Sichel, 1865Sphecodes sudai Tsuneki, 1983Sphecodes sulcatulus Cockerell, 1906Sphecodes sulcifera Tsuneki, 1983Sphecodes tadschicus Blüthgen 1935Sphecodes taicho Tsuneki, 1983Sphecodes tainoi Engel, 2006Sphecodes tanoi Tsuneki, 1983Sphecodes tantalus Nurse, 1903Sphecodes tertius Blüthgen, 1927Sphecodes togoanus Strand, 1912Sphecodes tomarchioi Nobile & Turrisi, 2004Sphecodes townesi Mitchell, 1956Sphecodes transversus Cockerell, 1919Sphecodes trentonensis Cockerell, 1913Sphecodes tristellus Cockerell, 1919Sphecodes tuckeri Friese, 1925Sphecodes turanicus Astafurova & Proshchalykin, 2017Sphecodes turneri Cockerell, 1916Sphecodes ugandae Blüthgen, 1928Sphecodes utinamius Tsuneki, 1983Sphecodes vachali Meyer, 1920Sphecodes variabilis Schrottky, 1906Sphecodes veganus Cockerell, 1904Sphecodes villosulus Schwarz, 2010Sphecodes vumbuensis Blüthgen, 1928Sphecodes walteri Nobile & Turrisi, 2004Sphecodes washingtoni Cockerell, 1904Sphecodes wheeleri Mitchell, 1956Sphecodes woodi Cockerell, 1945Sphecodes zangherii Noskiewicz, 1931