This article will soon be available in Spanish
Inspired by Mike Van Valen's "The Ratsnake Mess for Dummies"
Please note that the information in this article is current as of March 2018 (no later)
Please contact me or leave a comment if you spot an error
Please note that the information in this article is current as of March 2018 (no later)
Please contact me or leave a comment if you spot an error
Arguably House Snakes are much more of a mess than ratsnakes, which makes sense when you consider that they are they distributed over an area almost 7 times larger, including areas as diverse as the Sahara Desert, Congo Rainforest, Great Rift Valley, East African Savannah, Ethiopian Highlands, Okavango Delta, and Southern African Great Escarpment, and occur in a total of 46 countries, many of which have perennially turbulent political climates. It's no surprise that the number of herpetologists working in Africa is dwarfed by the number working in North America, and the vast majority of these people have not been of African descent (although that is beginning to slowly change).
African House Snake (Boaedon fuliginosus) from the northernmost part of the range in Morocco. Like everywhere in Africa, there are probably multiple undescribed cryptic species within this lineage |
When most people think of African House Snakes, the scientific name that probably comes to mind is Lamprophis fuliginosus. In this article, I'll try to explain why this well-known species had to be moved into the genus Boaedon in 2011, and why it will probably be split up into multiple species sometime in the (hopefully-not-too-distant) future. The correct scientific name of many African House Snakes in captive breeding colonies may be difficult or impossible to determine, especially because most people don't know which part of Africa their House Snakes originally came from (and they may have since been bred with House Snakes from other parts of Africa).
Simplified phylogenetic tree of Lamprophiinae, with focus on "house snakes" (genera Boaedon & Lamprophis). There's enough uncertainty about the structure within Boaedon that I didn't try to represent much of what's known. For more detailed trees, see the Kelly, Greenbaum, & Trape papers. Green are species lacking genetic data that can't be placed yet. Red stars are multiple cryptic species (there could be more). Click here for a larger version |
A great deal of clarity was gained from the taxonomic actions of Chris Kelly & co-authors in 2011, who split the species in the genus Lamprophis up into several genera, depending on their relationships to other genera of lamprophiines. Even this study was only able to include data on ~40% of the species of lamprophiine snakes, so it's probable that surprises and new discoveries still await us.
Swazi Rock Snakes, Inyoka swazicus, are endemic to rocky outcrops in Swaziland and adjacent provinces of South Africa |
The Olive Water Snake, Lycodonomorphus inornatus, was formerly thought to be a Lamprophis |
Fisk's House Snake, Lamprophis fiskii, is found in rocky & sandy areas in the western part of South Africa |
Olive House Snakes, Boaedon olivaceus are found in forests rather than savannah & grassland habitats |
Three other species get to stick around in Lamprophis for now: "L." abyssinicus and "L." erlangeri from the Ethiopian highlands, and "L." geometricus from the Seychelles. Probably once we get genetic data from these they will be moved into another genus, possibly Boaedon.
Most of the tree from Greenbaum et al. 2015, showing the paraphyly of B. fuliginosus with respect to other Boaedon species, and the geographic diversity of the samples. |
Which, if any, of these future species will get to keep the name fuliginosus is not clear, because these decisions are made based on the location of the original specimen, called the "type locality". The type locality for L. fuliginosus was originally and incorrectly reported in 1827 as "Java". People were more careless back then. There is also no clear type specimen; at one point, one was designated, but it was lost by 1965. The type locality was subsequently corrected to the more accurate but still completely unhelpful "Africa" in 1962, and further restricted to either South Africa or Ghana, but which one isn't clear.
Finally, there is the issue of Boaedon "capensis", a putative species described in 1997 by Hughes and occurring east of a hazy and ill-defined zone angling northeast-southwest from the Gulf of Aden along the Great Rift Valley, then turning east and extending to the Atlantic Ocean possibly near the Angola-Namibia border, but potentially as far north as the mouth of the Congo River and thus also including three of the largest and most poorly-surveyed countries in Africa: Angola, the Democratic Republic of the Congo, and Sudan (including the still relatively new country of South Sudan). This name effectively replaces fuliginosus in eastern and southern Africa, but the exact boundaries are not remotely known, and it will probably turn out that both species are non-mutually-exclusive complexes of cryptic species. Because of the type locality confusion of fuliginosus, it could even turn out that both names (fuliginosus and capensis) are the same southern African species5, and that the western and central African species will need new names.
Map of the species currently in Boaedon & Lamprophis
Question marks indicate areas where the species range
is uncertain (pink=lineatus complex, green=olivaceus,
brown="fuliginosus"/"capensis" complex)
Click
here for larger version
|
Boaedon radfordi, a new species from the Uganda-DRC border region. From Greenbaum et al. 2015 |
Boaedon longilineatus, a new species from Chad From Trape & Mediannikov 2016 |
Boaedon capensis from South Africa |
In case you lost count, a quick recap of species that are or have been in Lamprophis:
- Hormonotus modestus (Yellow Forest Snake or "Uganda House Snake"; moved in 1850s)
- Inyoka swazicus (Swazi Rock Snake or "Swaziland House Snake"; moved in 2011)
- Pseudoboodon lemniscatus (briefly in Lamprophis in 1904, barely counts, see footnote2)
- Lycodonomorphus inornatus (originally described as a Lamprophis because it was terrestrial, but always a little weird; moved in 2011)
- Lycodonomorphus rufulus (briefly in Lamprophis 1840s-1860s, barely counts)
- Lamprophis aurora (type species for the genus, will always be a Lamprophis by definition)
- Lamprophis fiskii (gets to stick with aurora)
- Lamprophis fuscus (gets to stick with aurora)
- Lamprophis guttatus (gets to stick with aurora)
- "Lamprophis" abyssinicus (awaiting DNA data; Ethioipian highlands)
- "Lamprophis" erlangeri (awaiting DNA data; Ethioipian highlands)
- "Lamprophis" geometricus (awaiting DNA data; Seychelles)
- Boaedon lineatus (type species for the genus, will always be a Boaedon by definition, although as defined it too is likely a cryptic species complex)
- Boaedon virgatus (gets to stick with lineatus)
- Boaedon olivaceus (gets to stick with lineatus)
- Boaedon maculatus (awaiting DNA data; got to stick with the above 3 because of morphology; Horn of Africa)
- Boaedon radfordi (described by Greenbaum et al. 2015, split from olivaceus)
- Boaedon upembae (formerly Lycodonomorphus subtaeniatus upembae; moved by Greenbaum et al. 2015; in the B. virgatus group)
- Boaedon littoralis (split from B. lineatus by Trape & Mediannikov 2016, but lacks DNA data)
- Boaedon longilineatus (split from B. lineatus by Trape & Mediannikov 2016)
- Boaedon paralineatus (split from B. lineatus by Trape & Mediannikov 2016)
- Boaedon perisilvestris (the first of many cryptic species to be split from B. fuliginosus; by Trape & Mediannikov 2016)
- Boaedon subflavus (the 2nd split from B. fuliginosus by Trape & Mediannikov 2016)
- Boaedon capensis (replaces fuliginosus in east Africa, could be multiple cryptic species)
- Boaedon fuliginosus (definitely at least 7 cryptic species, probably many more, no guarantee that any will be called fuliginosus)
The Aurora House Snake, Lamprophis aurora, is the type species of the genus Lamprophis, meaning it will always be in Lamprophis unless that genus goes away completely |
There's further debate about the utility of splitting up cryptic species complexes, especially if it makes it almost impossible to identify which species you're looking at by morphology alone. These same issues are recapitulated in the North American ratsnake taxonomic "mess", North American slimy salamanders, egg-eating snakes, and in countless other species groups around the world. When I was writing this article, I thought more than once that I should just wait for a better time when it's all stabilized, but actually there's never a good time; we're always learning more. Ultimately, fleshing out and revising phylogenies and taxonomies will teach us a lot about biodiversity, evolution, and human nature. My advice is to try to be open-minded rather than bitter and ugly when discussing them. There is no "right" or "wrong", there are just rules we've (mostly) agreed to follow. It's an exciting time.
If this group of snakes interests you, watch the labs of Christopher Kelly, Jakob Hallermann, Aaron Bauer, and Jean-François Trape for future research that should make much of this article obsolete.
If this group of snakes interests you, watch the labs of Christopher Kelly, Jakob Hallermann, Aaron Bauer, and Jean-François Trape for future research that should make much of this article obsolete.
Edit: In July 2020, writing in the in the African Journal of Herpetology, Hallermann et al. provide the first DNA data for geometricus, proving as suspected that it belongs in Boaedon. They also revalidate mentalis and angolensis and describe three new species of the fuliginosus complex from Angola (named bocagei, branchi, and fradei). Their analysis continues to suggest numerous undescribed species elsewhere in Africa. They restrict fuliginosus to western Africa from Morocco to northern Angola, although it seems likely that it could be restricted further. They also provide a morphological key to the now nine species of Boaedon in Angola.
Edit: In January 2021, again in the African Journal of Herpetology, Ceríaco and colleagues describe two new species from the islands of São Tomé (Boaedon bedriagae) and Príncipe (Boaedon mendesi) in the Gulf of Guinea off Africa's west coast, which were previously mostly considered a subspecies or synonym of either fuliginosus or lineatus. They also state that "Given the considerable number of names coined as subspecies of either fuliginosus or lineatus, the number of names currently considered as synonyms of these two species and the imprecise data about the type locality of the nominotypical forms, this revision may prove to be one of the most challenging taxonomic works of present-day African herpetology."
Edit: A new paper published in the journal Salamandra on 30 October 2022 led by Arthur Tiutenko re-evaluated the two Ethiopian highland endemics, abyssinicus and erlangeri. Both are removed from Lamprophis but neither belongs to Boaedon. Instead, abyssinicus is assigned to Pseudoboodon on the basis of morphology (still no DNA data are available). The first DNA data for erlangeri are published, from a specimen collected in 2016. Because it is more closely related to Bothrophthalmus and Bothrolycus than it is to other lamprophiines, erlangeri is assigned to a brand new genus, Bofa (an Oromo word for "snake"). Color photos in life, CT scans of the skull, and detailed morphological comparisons with the other genera are graciously provided. They suggest "bofa(s)" or "Ethiopian forest snakes" as common names. In addition, guttatus is removed from Lamprophis and assigned to Alopecion, an "empty" genus originally used in the 1850s for guttatus and various other species, all of which have since ended up in other genera. I didn't see this last one coming, but it makes sense because guttatus shares a common ancestor with the other three Lamprophis (aurora, fiskii, and fuscus) less recently than those three share an ancestor with one another, and guttatus is a rocky habitat specialist that has morphological adaptations that allow it to flatten the head to a great degree, in contrast to other Lamprophis that have relatively rounded heads. Admittedly, this is rather subjective, but the authors note that there might be cryptic species within guttatus that would perhaps benefit from being part of a genus that is morphologically, ecologically, and genetically distinct, however arbitrarily the lines between genera are often drawn.
Edit: A new paper published 30 November 2022 in the bulletin of the French herpetological society described a new species of Boaedon from mountainous areas in Rwanda, Burundi, Uganda, Tanzania, and the DRC as Boaedon montanus, effectively splitting it from fuliginosus/lineatus in that area.
1 Note the difference between the endings of the family ("-idae") and subfamily ("-inae") names.↩
2 Except for Pseudoboodon lemniscatus, but that was only once, in 1904. It counts, but only in the same way as stuff you did once in college. This is complicated enough already.↩
3 Sources differ on whether B. lineatus is distinct from B. fuliginosis, but it seems to be in western Africa (though both could be multiple cryptic species). Some resources use B. lineatus for house snakes with head stripes in e.g. Uganda, Ethiopia, and Sudan, but increasingly these are referred to as B. capensis. Characteristics used to distinguish B. virgatus & B. olivaceus from B. fuliginosus/capensis/lineatus include undivided subcaudal scales in B. olivaceus and only 23 dorsal scale rows in B. virgatus, as well as the fact that B. virgatus & B. olivaceus are found in forests whereas the others are savannah species.↩
4 The presence or absence of head stripes has been used as a highly visible character, but ultimately this probably won't prove to be closely correlated with genetic variation (and it's complicated by the fact that some Boaedon populations have head stripes as juveniles but lose them as adults). This is also the case in North American ratsnakes, where former subspecies with radically different adult color patterns, like E. o. rossalleni and E. o. quadrivittata turned out to be so genetically similar to the more widespread black phenotype that they are now not recognized. This is part of a move away from the subspecies concept in general, wherein many authors either synonymize subspecies with existing species as "mere variants" or elevate them to full species status using genetic data. I think we can expect this trend to continue with House Snakes.↩
5 This could happen if South Africa is chosen as the type locality of fuliginosus, because the type locality of capensis is also in South Africa—if South Africa ultimately contains just one species from the fuliginosus complex, then it will get to keep the older name (fuliginosus), and other former members elsewhere should not use the name capensis in order to avoid further confusion. If the type locality of fuliginosus is chosen to be in Ghana instead, then the name will probably continue to be used in western Africa. Let us hope for the 2nd option.↩
6 This isn't an identification guide, but if you want to see the scale characters for the different species, you can refer to the tables and descriptions in the Kelly, Greenbaum, and Trape papers.↩
7 "B. fuliginosus" are also found on the Arabian peninsula in Yemen; this could be the most obvious future split if these are shown to be their own lineage, and several sources have already used the name arabicus for them, although just a few individuals are known and additional biological specimens from Yemen are hard to come by. A recent paper used bedriagae as the name of a full species on the islands of São Tomé, with a new species being described from the neighboring island of Príncipe.↩
ACKNOWLEDGMENTS
Thanks to Peter Uetz for his advice on literature, and to Konrad Mebert, Cliff & Suretha Dorse, and Dan Rosenberg for the use of their photos.
REFERENCES
For map references, see map inset
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Bogert, C. M. 1940. Herpetological results of the Vernay Angola Expedition. Part 1. Snakes, including an arrangement of African Colubridae. Bulletin of the American Museum of Natural History 77:1-107 <link>
Branch, W. R. 1984. The House Snakes of southern Africa (genus Lamprophis). Litteratura Serpentium 204:106-120 <link>
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Broadley, D. G. 1969. The African house snakes—How many genera? The Journal of the Herpetological Association of Africa 5:6-8 <preview>
Ceríaco, L. M., M. P. Marques, and A. M. Bauer. 2018. Miscellanea Herpetologica Sanctithomae, with a provisional checklist of the terrestrial herpetofauna of São Tomé, Príncipe and Annobon islands. Zootaxa 4387:91-108.
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Visser, J. 1979. Notes on two rare house snakes – Part 1. Lamprophis fiskii Boulenger (1887) and L. swazicus Schaefer (1970). Journal of the Herpetological Association of Africa 19:10-13.
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Visser, J. 1979. Notes on two rare house snakes – Part 1. Lamprophis fiskii Boulenger (1887) and L. swazicus Schaefer (1970). Journal of the Herpetological Association of Africa 19:10-13.
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Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.