Research Article |
Corresponding author: Silas Bossert ( sb2346@cornell.edu ) Academic editor: Michael Ohl
© 2019 Silas Bossert.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Bossert S (2019) Monotypic no more – a new species of the unusual genus Schwarzia (Hymenoptera, Apidae, Biastini). Journal of Hymenoptera Research 69: 23-37. https://doi.org/10.3897/jhr.69.32966
|
Schwarzia elizabethae Bossert, sp. n., a previously unknown species of the enigmatic cleptoparasitic genus Schwarzia Eardley, 2009 is described. Both sexes are illustrated and compared to the type species of the genus, Schwarzia emmae Eardley, 2009. The male habitus of S. emmae is illustrated and potential hosts of Schwarzia are discussed. Unusual morphological features of Schwarzia are examined in light of the presumably close phylogenetic relationship to other Biastini. The new species represents the second species of Biastini outside the Holarctic region.
Bees, cleptoparasitism, East Africa
Biastini (Apidae, Nomadinae) is a small tribe of cleptoparasitic bees with just 13 described species in four genera (
The fourth genus and the most recently described biastine bee was Schwarzia emmae Eardley, 2009. It is an enigmatic bee with bizarre morphological characters that required the description of a new genus.
Up to now, Schwarzia was only known from the type species and from very few records. All localities are in Eastern Africa, thereby rendering the genus the only Biastini outside the Holarctic (
Specimens were collected in Kenya during four collecting events in 1998 and 1999. The type locality of the newly described species is in Tsavo East National Park in eastern Kenya, which is dominated by xeric plains and savanna habitats. As all specimens were collected in Malaise traps, no information on flower visitation is available. Photographs were taken with a Macropod Pro imaging system, consisting of a Canon EOS 6D camera and a Stackshot 3× Cognisys device. Z-stacking was carried out with Zerene Stacker Pro stacking software v1.04. The distribution map was generated with SimpleMappr (
The holotype is deposited in the type collection of the National Museums of Kenya (
The following abbreviations are used in the description: tergum (T), sternum (S), flagellomere (FL). For the description of the male, morphometric measures are given as a range from the smallest to the largest specimen examined.
KENYA: Eastern Province, at Athi River, Tsavo East National Park, 2°38.51'S, 38°21.98'E, 22.-29.XI.1999, leg. R. Copeland, Malaise trap, 5♂, 1♀. Eastern Province, at Athi River, Tsavo East National Park, 2°38.51'S, 38°21.98'E, 29.III-1.IV.1999, leg. R. Copeland, Malaise trap, 1♂.
Forewing with two submarginal cells, first of which at least twice as long as second (Fig.
Comparison of selected diagnostic characteristics of males of Schwarzia elizabethae Bossert, sp. n. (left column: A, C, E, G) vs. S. emmae Eardley, 2009 (right column: B, D, F, H) A–B discs of T1 and T2 C–D head characteristics in lateral view. Arrows point to finely pitted protrusions on frontal area of S. emmae and to the intended inner margin of the compound eye E–F antennae G–H tegulae.
Male (Fig.
Comparison of selected diagnostic characteristics of females of Schwarzia elizabethae Bossert, sp. n. (left column: A, C, E) vs. S. emmae Eardley, 2009 (right column: B, D, F) A–B discs of T1 and T2 C–D head characteristics in lateral view. Arrows point to finely pitted protrusions on frontal area of S. emmae and to the intended inner margin of the compound eye E–F details of T5. Arrows point to the differently curved median area of the disc.
Female (Fig.
Males of both described species of Schwarzia have only 10 flagellomeres. For nearly all species of bees, male individuals have 11 flagellomeres and females have 10 (
KENYA: Eastern Province, base of Ukasi Hill, 0°49.262'S, 38°32.666'E, 21.XI.-05.XII.2011, leg. R. Copeland, Malaise trap, Acacia/Commiphora savanna, 1♀. Eastern Province, base of Ukasi Hill, 0°49.201'S, 38°32.627'E, 5.-12.V.2018, leg. R. Copeland, Malaise trap, Acacia/Commiphora savanna, 1♂. Eastern Province, Mulu Musingila farm, 2°6.847'S, 38°14.393'E, 13.-27.XII.2016, leg. R. Copeland, Malaise trap, farmland near small seasonal wet area, 1♂. All additional records are deposited in the ICIPE collection, Nairobi, Kenya.
The species is known from four different localities, all of which are in the former Eastern Province of Kenya (Fig.
KENYA: Rift Valley Province, Mathews Range, Sarara Camp, 1.1°N, 37.387°E, 10.-13.VI.1998, leg. R. Copeland, Malaise trap, 1♂, 1♀, dep. in
With two newly reported collecting sites, the species is now known from a total of five different localities in Kenya and Tanzania (Fig.
Schwarzia are unusual bees that can easily be recognized and distinguished from other cleptoparasitic bees in the Afrotropical region. Nonetheless, the discovery of a new and distinctly different species allows us to refine the diagnosis of the genus and re-evaluate characters that were previously thought to be diagnostic. First, the pre-apical tooth described as diagnostic for the genus (
The reduced number of antennal segments in Schwarzia males is indicative of a close relationship to other Biastini. Reduced flagellomeres of males are generally rare in bees but occur more frequently in certain tribes of cleptoparasitic Apidae. In Ammobatini, males of Pasites Jurine, 1807, Melanempis Saussure, 1890, Parammobatodes Popov, 1932 and Chiasmognathus Engel, 2006 have reduced numbers of flagellomeres (
An interesting and prominent morphological difference between S. emmae and S. elizabethae are the finely punctate supraclypeal protrusions of S. emmae, which are entirely absent in S. elizabethae (Figs
Due to the lack of field observational data for Schwarzia, the biology of both species is essentially unknown. All presently available material was collected with traps and therefore no information on flower visitation or potential host(s) is available. Nonetheless, the morphology and presumably close phylogenetic relationship to Biastes leaves no doubt that Schwarzia has a cleptoparasitic lifestyle. All Biastini are cleptoparasites of species of Rophitinae (
Schwarzia and the potential host Systropha even share certain morphological features: both sexes have an unusually long glossa, which is rather uncommon for cleptoparasitic bees. The long mouthparts suggest that Schwarzia bees collect nectar at flowers with a deep corolla, and therefore may even visit the same flowers as their potential host Systropha, which are specialists on flowers of the morning glory family (Convolvulaceae;
Collecting event 1 (near the Sarara Camp, 10.-13.VI.1998; collection site of S. emmae): Afranthidium Michener, 1949, Amegilla Friese, 1897, Braunsapis Michener, 1969, Ceratina Latreille, 1802, Macrogalea Cockerell, 1930, Macronomia Cockerell, 1917, Maynenomia Pauly, 1984, Nubenomia Pauly, 1980, Seladonia Robertson, 1918, Thrinchostoma de Saussure, 1890.
Collecting event 2 (in Tsavo East National Park, 10.VI.1998; collection site of S. emmae): Acunomia Cockerell, 1930, Afromelecta Lieftinck, 1972, Amegilla, Anthidium Fabricius, 1804, Ceratina, Coelioxys, Lasioglossum s.l. Curtis, 1833, Lipotriches Gerstaecker, 1858 subgenus Patellotriches Pauly, 2014, Lipotriches subgenus Stellotriches Pauly, 2014, Macronomia, Megachile Latreille, 1802, Meganomia Cockerell, 1909, Mermiglossa Friese, 1912, Nubenomia, Pseudapis (s. str.) Kirby, 1900, Seladonia, Sphecodes Latreille, 1804, Thyreus Panzer, 1806.
Collecting event 3 (in Tsavo East National Park, 22.-29.XI.1999; collection site of S. elizabethae): Amegilla, Braunsapis, Coelioxys, Lipotriches subgenus Stellotriches, Macrogalea, Maynenomia, Megachile, Pasites Jurine, 1807, Pseudapis (s. str.).
Collecting event 4 (in Tsavo East National Park, 29.III-1.IV.1999; collection site of S. elizabethae): Pasites.
Non-parasitic bees were only collected in collecting events 1, 2, and 3. The only bee genus that was collected during all these three events is Amegilla, an apid bee genus in the subfamily Anthophorinae (
The species examined in this study are part of a donation of insects made by Robert Copeland to the U.S. National Museum of Natural History. I thank him for his support to develop this study. I further thank Matthew Buffington (USDA-ARS) for granting access to the imaging system, and Laurence Packer, Michael Orr, and Michael Kuhlmann for discussion on the manuscript. Lastly, I thank Simon van Noort (Iziko South African Museum) for correspondence concerning S. emmae. This work was supported by a U.S. National Science Foundation (NSF) grant to Bryan N. Danforth, Seán G. Brady, James P. Pitts, and Robert M. Ross (DEB-1555905), and a Peter Buck predoctoral fellowship at the Smithsonian Institution to the author.