Field of Science

Allendesalazaria nymphoides, the Hidden Blister Beetle

The blister beetles of the family Meloidae have attracted attention for a number of reasons. One is their production of caustic defensive chemicals which may be powerful enough to cause severe injury to humans or their livestock. Another is their remarkable life cycles. Many blister beetles develop as nest predators or kleptoparasites of bees. The larvae of these species are hypermetamorphic with the first instar being more mobile than later stages. These mobile larvae will find bees and latch onto them so that they can be carried to the host's nest.

Allendesalazaria nymphoides, copyright Stanislav Krejcik.


This association reaches an extreme in Allendesalazaria nymphoides of north-west Africa. This reclusive species has, to date, been recorded from localities in Morocco, Algeria and Mauritania (Bologna & Aberlenc 2002). It is readily distinguished from other blister beetles by its much-reduced elytra which are oval and widely separated from each other. It is also distinguished by claws that lack the free lower blade found in most other meloids (Bologna & Pinto 2002). Whether they produce the noxious chemicals known from other members of their family, I haven't found a record.

Allendesalazaria nymphoides develops in the nests of solitary burrowing bees of the genus Anthophora. Adults of A. nymphoides do not feed, and never emerge from the nest in which they matured. Instead, they lay their own eggs within that same nest. Dispersal is then left to the hatching larvae that (I presume) latch onto those emerging bees that escaped their parents' depredations. Eventually, the new generation of bees will establish nests of their own. And when they do, the blister beetles will be ready for them.

REFERENCES

Bologna, M. A., & H.-P. Aberlenc. 2002. Allendesalazaria, un nouveau genre de Meloidae pour la faune saharienne (Coleoptera). Bulletin de la Société Entomologique de France 107 (2): 191–192.

Bologna, M. A., & J. D. Pinto. 2002. The Old World genera of Meloidae (Coleoptera): a key and synopsis. Journal of Natural History 36 (17): 2013–2102.

Pied Harvestmen of the Antilles

Harvestmen of the Neotropical family Cosmetidae have been featured on this site a couple of times before. Each time, I've commented on the dire taxonomic state of this diverse family, with many genera being poorly or inaccurately defined. Thanks to extensive (and continuing) studies in recent years by Braxilian researchers and their associates, this situation has been progressively improving, but we still have a lot to learn.

Cynortoides sp., copyright Damion Laren Whyte.


Cynortoides is a genus currently holding ten species of cosmetid. Most of these are found on the islands of the Greater Antilles—Cuba, Jamaica and Hispaniola—though the genus has also been recorded from adjoining regions of Mexico and Venezuela (Kury 2003). As with other cosmetids, Cynortoides has historically been defined largely be features of the external spination, including a lack of spines on the legs, two pairs of spines in the rear part of the dorsal scutum, and no spines on the free abdominal segments (Mello-Leitão 1933). Also as with other cosmetid genera, Cynortoides species are colourfully patterned. The name of one species, C. v-album, refers to its characteristic bright white V marking on the back (though personally, I would describe the pattern as more of a Y).

Though this genus does not yet appear to have been revised in detail, some of its species were included in a recent broader study of cosmetid phylogeny by Medrano et al. (2021). They found strong support for an association between the Cuban C. cubanus and the Hispaniolan C. v-album, together with two other Cuban species previously included in the related genus Cynorta. These last two species were consequently transferred to Cynortoides though Medrano et al. did not comment on whether this affected the genus' established diagnosis. The authors speculated that further studies might prove Cynortoides to be a strictly Greater Antillean genus with mainland records being misplaced. Cynortoides would not be unique in this regard: the islands of the Caribbean are home to a number of lineages found nowhere else, reflecting a long history independent of the adjoining continents.

REFERENCES

Kury, A. B. 2003. Annotated catalogue of the Laniatores of the New World (Arachida, Opiliones). Revista Ibérica de Aracnología, special monographic volume 1: 1–337.

Medrano, M., A. B. Kury & A. C. Mendes. In press 2021. Morphology-based cladistics splinters the century-old dichotomy of the pied harvestmen (Arachnida: Gonyleptoidea: Cosmetidae). Zoological Journal of the Linnean Society.

Mello-Leitão, C. F. de. 1933. Notas sobre os opiliões do Brasil. Descritos na obra postuma de Sörensen: "Descriptiones Laniatorum". Boletim do Museu Nacional 9 (1): 99–114.

The Race of Racers

Snakes are, for the most part, fairly retiring animals, little seen even in areas where they may be abundant. In much of North America, however, one of the most commonly encountered snake species is the racer Coluber constrictor. This moderately large non-venomous snake, with the largest individuals approaching two metres in length, is a widespread inhabitant of open habitats such fields, brushland or open woodlands. Its distribution is centred over much of the continental United States, being found in most regions except much of the arid south-west. Outside the United States, it has a very patchy distribution in southernmost Canada, Mexico and northern Central America. Most recent authors treat it as the sole species in the genus Coluber; other species historically assigned to this genus from across the Holarctic region now being treated as separate. These include the North American whip snakes of the genus Masticophis, believed to the closest relatives of the racer (Myers et al. 2017).

Southern black racer Coluber constrictor priapus, copyright Peter Paplanus.


Adult racers are generally uniformly dark in coloration dorsally, with a lighter-coloured venter, though juveniles have a blotchy checkered pattern (Fitch 1963). The exact shade varies across the species' range and a number of subspecies have been recognised such as the blue racer Coluber constrictor foxii and the northern black racer C. c. constrictor. In general, individuals are darker towards the east and north, and lighter towards the west and south. Wilson (1978) listed eleven subspecies of C. constrictor whereas a phylogeographic study of the species by Burbrink et al. (2008) identified six major lineages. As well as coloration, members of these lineages may differ in factors such as behaviour or genital morphology, and future studies may see them elevated to the rank of separate species.

Blue racer Coluber constrictor foxii, copyright Peter Paplanus.


The natural history of Coluber constrictor was reviewed in detail by Fitch (1963). As the vernacular name of 'racer' suggests, Coluber constrictor is a fast mover. Its diet contains a mixture of small vertebrates, such as frogs, lizards and small mammals, and large invertebrates such as grasshoppers, crickets and caterpillars. Foraging individuals often hold the front end of the body raised above the ground. Despite their species name, racers do not kill their prey by constriction. Instead, they mostly capture prey by darting forward quickly and grabbing it, often swallowing prey live. Fitch recorded one occasion when he observed a racer in the process of subduing a large skink. While the snake was swallowing its prey, Fitch attempted to capture it. The racer disgorged the skink, and both snake and lizard escaped the scene. Diet may vary with size, with smaller individuals taking a higher proportion of invertebrates, but also varies with range. Populations in the west may primarily feed on insects whereas others may almost exclusively take vertebrates. The northern black racer of the northeastern United States is the most inclined of the subspecies to feed on other snakes. Cannibalism is not unknown; at least one author recorded observing it among broods raised in captivity. In one case, two young racers latched onto a single lizard. One of them successfully downed the lizard, and then also continued on to devour the snake attached to the other end, despite the swallowed snake being nearly as large as its swallower.

Eastern yellow-bellied racer Coluber constrictor flaviventris, copyright David Sledge.


During winter, racers hibernate in crevices and hollows among rocks. Preferred hibernation locations are often at the top of hills, away from their usual hunting sites. Mating and egg-laying occurs shortly after emergence with the peak of egg-laying being in early June (Rosen 1991). Racers, particularly the large northern black, may become more aggressive during this period. Eggs are buried shallowly, in loose soil or under litter, though females may take advantage of abandoned mammal burrows to provide a more secure location. As with other snakes, laying seems to be a matter of pump and dump; I didn't come across any references to females protecting clutches. After hatching, males take about a year to reach sexual maturity whereas the larger females take about two years. Fitch (1963) reports encountering the same individuals over the course of several years (recognisable by their bearing the scars of prior collection of scale samples). Nevertheless, the majority of racer hatchlings do not survive their first summer. Few get the opportunity to seek out shelter for their winter's sleep.

REFERENCES

Burbrink, F. T., F. Fontanella, R. A. Pyron, T. J. Guiher & C. Jimenez. 2008. Phylogeography across a continent: the evolutionary and demographic history of the North American racer (Serpentes: Colubridae: Coluber constrictor). Molecular Phylogenetics and Evolution 47: 274–288.

Fitch, H. S. 1963. Natural history of the racer Coluber constrictor. University of Kansas Publications, Museum of Natural History 15 (8): 351–468.

Myers, E. A., J. L. Burgoon, J. M. Ray, J. E. Martínez-Gómez, N. Matías-Ferrer, D. G. Mulcahy & F. T. Burbrink. 2017. Coalescent species tree inference of Coluber and Masticophis. Copeia 105 (4): 640–648.

Wilson, L. D. 1978. Coluber constrictor Linnaeus. Catalogue of American Amphibians and Reptiles 218: 1–4.

The Cephalodiscids

Among the more obscure inhabitants of the world's oceans are the Cephalodiscidae, a family of small (only a few millimetres in length), largely sessile animals that mostly live in colonies within a shared domicile. Though rarely observed, cephalodiscids have received their fair share of attention due to being among the closest living relatives of the graptolites that once dominated the world's oceans during the early Palaeozoic era.

Preserved Cephalodiscus colony, copyright E. A. Lazo-Wasem.


Cephalodiscids are one of the two living branches of the pterobranchs (the other being the Rhabdopleuridae), which together with the acorn worms make up the phylum Hemichordata. Hemichordates are in turn one of the three living phyla of the deuterostomes, together with the echinoderms and chordates (to which, of course, we ourselves belong). Pterobranchs are filter feeders, using an arrangement of tentaculated arms arising just behind the head to collect particles from the water. In cephalodiscids, each individual usually possesses multiple pairs of arms in contrast to the single pair in rhabdopleurids (though at least one species of Cephalodiscus has small males with a single pair). The head carries a large glandular disc (hence the name of the family) that is used to secrete the horny tissue making up the external dwelling (referred to as the tubarium) in which a colony of Cephalodiscus lives. Both cephalodiscids and rhabdopleurids have a contractile stalk at the end of the body from which new individuals (zooids) are budded. However, whereas the zooids of rhabdopleurids (and presumably their extinct graptolite relatives) remain attached to each other throughout their life, cephalodiscid zooids split away from their parent by the time they mature. The majority of cephalodiscid species have distinct males and females though a small number may be hermaphrodites. Some species exhibit sexual dimorphism; males may be considerably smaller than females.

Individual zooid of Cephalodiscus dodecalophus, from Sedgwick et al. (1898).


About twenty species of living cephalodiscids are currently recognised. The majority of these have been included in a single genus Cephalodiscus, albeit divided between a number of subgenera. The single outlier, Atubaria heterolopha, was described in 1936 from a single dredge haul near Japan (Mitchell et al. 2013). No dwelling material was found in the haul so it was presumed this species does not construct a tubarium like other cephalodiscids. However, its zooids were otherwise little different from those of Cephalodiscus. The subgenera of Cephalodiscus are mostly distinguished by tubarium structure. In some species, each individual in the colony will have its own separate tube closed off at the base. In other species, tubes will open into a central chamber shared between multiple zooids (Maletz 2014). Openings of the tubarium may be surrounded by spines and the like, secreted by the zooids as they creep out from their domicile.

Recent studies have indicated that cephalodiscids represent the sister group to all other pterobranchs/graptolites, implying an history that may extend back to the Cambrian. However, the fossil record of cephalodiscids themselves is minimal. This is largely due to practical difficulties: because the soft-bodied zooids are not preserved, fossils can only be identified from the external tubarium structure alone. Unless the origin point of the tubarium is preserved and identifiable, there is little to distinguish a cephalodiscid tubarium from a benthic graptolite (graptolite colonies begin with a differentiated larval chamber called a sicula, cephalodiscids produce no such structure). A handful of fossil cephalodiscids have been identified, notably the early Devonian Eocephalodiscus, but as yet they tell us little about the evolution of this ancient lineage.

REFERENCES

Maletz, J. 2014. The classification of the Pterobranchia (Cephalodiscida and Graptolithina). Bulletin of Geosciences 89 (3): 477–540.

Mitchell, C. E., M. J. Melchin, C. B. Cameron & J. Maletz. 2013. Phylogenetic analysis reveals that Rhabdopleura is an extant graptolite. Lethaia 46: 34–56.

Lilies of Blood

The flora of southern Africa is renowned for being remarkably diverse and, in many cases, remarkably eye-catching. The region is home to more than its fair share of ornamental plants, many of which have become popular garden subjects. Among the remarkable members of the southern African flora are the blood lilies of the genus Haemanthus.

Haemanthus coccineus, copyright Peter Coxhead.


Haemanthus is a genus of 22 known species found in the very southern part of the continent, in the countries of South Africa and Namibia (species from further north that have historically been included in Haemanthus are now treated as a separate genus Scadoxus). It is a member of the belladonna family Amaryllidaceae and, like many other members of that family, grows as a herb from a fleshy bulb that is partially or entirely concealed underground. The plant above ground may be annual or persistent, depending on species. Each individual Haemanthus plant produces very few leaves at a time: two is the most common number (Van Jaarsveld 2020). The leaves are more or less fleshy, often hairy, and may be directed upwards or spread outwards.

In those species that shed their leaves, flower stalks are produced before the next season's leaves appear, in a similar matter to the related naked ladies Amaryllis belladonna. Flowers are produced in dense umbels, subtended by bracts that are often brightly coloured, so at a glance the inflorescence of some species might be taken for a single large flower up to ten centimetres in diameter. Depending on the species, the supporting stalk may vary from over a foot in height to only a few centimetres. The first species to be described bear flowers of a bright red colour, explaining both the genus and vernacular names, but flowers may also be pale pink or white. Species that lack the red colour may be referred to as 'paintbrush lilies' rather than 'blood lilies'. Fruits are soft fleshy berries.

Haemanthus albiflos, copyright Krzysztof Ziarnek, Kenraiz.


Phylogenetic analyses of the genus have identified two major clades, a mostly eastern clade found in regions with summer rainfall and a mostly western clade associated with winter rainfall. A notable outlier is the eastern summer-rainfall species H. montanus which is the sister taxon to the winter rainfall clade. Members of the summer-rainfall clade have white or pale pink flowers; members of the winter-rainfall clade have pale pink to dark red flowers. Members of both clades have been grown as pot plants for their unusual appearance though the scent of the flowers is not regarded as pleasant. Perhaps the most widely grown species is H. albiflos, a species native to both the western and eastern parts of South Africa that bears flowers in umbels up to seven centimetres wide. This species is evergreen, carrying its leaves year-round.

REFERENCE

Van Jaarsveld, E. 2020. Haemanthus. In: Eggli, U., & R. Nyffeler (eds) Illustrated Handbook of Succulent Plants: Monocotyledons 2nd ed. pp. 441–443. Springer.

The Oligorhynchiidae

Dorsal view of Oligorhynchia subplana gibbosa, from Cooper (1935).


From Oligochiton, we move onto Oligorhynchia. The Oligorhynchiidae are a family of very small brachiopods known from the Middle and Late Ordovician. They were among the earliest representatives of the Rhynchonellida, a major group of brachiopods that survives to the present day. Rhynchonellidan shells are usually characterised by a strong beak associated in life with a well-developed pedicel. In oligorhynchiids, this beak is suberect and the shell as a whole is an elongate subtriangular shape. The valves of the shell are folded into coarse plicae (ridges). At least towards the base of the shells, the major folds are in what is called an inverted arrangement, with a ridge in the dorsal valve matched by a valley in the ventral valve (Schmidt & McLaren 1965). Other structural features defining the group include small plates projecting into the pedicel opening, distinct vertical dental plates and divided hinge plates in the valve articulation, and the usual absence of a median septum or cardinal process inside the shell (Savage 1996).

The oligorhynchiids first arose in the east of what was then the continent of Laurentia (corresponding to modern North America). They subsequently spread across the Iapetus Ocean to the continents of Baltica and Kazakhstan (Jin 1996). The end of the Ordovician saw their replacement by other rhynchonellid families. Nevertheless, their genetic lineage would continue for some time yet as they have been identified as ancestors of later families: the Trigonirhynchiidae and Camarotoechiidae (Jin 1989). The brief oligorhynchiid spark would blossom into later rhynchonellid success.

REFERENCES


Jin, J. 1989. Late Ordovician–Early Silurian rhynchonellid brachiopods from Anticosti Island, Quebec. Biostratigraphie du Paléozoïque 10: 1–127, 130 pls.

Jin, J. 1996. Ordovician (Llanvirn–Ashgill) rhynchonellid brachiopod biogeography. In: Copper, P., & J. Jin (eds) Brachiopods pp. 123–132. CRC Press.

Savage, N. M. 1996. Classification of Paleozoic rhynchonellid brachiopods. In: P. Copper, & J. Jin (eds) Brachiopods pp. 249–260. CRC Press.

The Fate of Oligochiton

Chitons are one of the most distinctive and evolutionarily divergent groups of molluscs alive today. But compared to other groups of molluscs, the fossil record of chitons is rather sparse—or at least sparsely studied. It's not hard to see why. The multi-plated nature of the chiton shell means that it tends to fall apart after death, and the structure of the plates is such that critical features are easily abraded.

(Clockwise from top left) head, intermediate and tail valves of Lepidochitona lioplax, from Dell'Angelo et al. (2011).


Lepidochitona lioplax is one example of a fossil chiton. It was originally described from Oligocene rocks belonging to the Sooke Formation of southern Vancouver Island in British Columbia. Only four moderate-sized valves were initially identified: one head valve, one intermediate, and two tails (so at least two individuals were involved). The valves had a smooth outer surface without a strong distinction in appearance between the central and lateral areas. The insertion plates (lateral projections of the lower surface of the valves that in life anchor them into the surrounding girdle) were very short. The sutural laminae (anterior projections of the lower surface of the intermediate and tail valves that articulate with the valve in front) were low, wide, and divided in the middle by a broad shallow surface. Slits in the lateral insertion plates were numerous, with several in the tail valves and probably two or three on each side in the intermediate valves (Smith 1960). When first described, this species was thought distinct enough to belong in its own genus Oligochiton.

Oligochiton lioplax would then go little reported on until 2011 when Dell'Angelo et al. described an assemblage of chiton fossil from the latest Eocene or early Oligocene of the Lincoln Creek Formation in Washington State. Specimens of lioplax were relatively numerous in this collection and Dell'Angelo et al. were able to examine close to a hundred valves. Their observations would lead to something of a downgrade in the species status. Rather than deserving its own extinct genus, Dell'Angelo et al. felt that lioplax could be comfortably accommodated in the living genus Lepidochitona. Its smooth valves are unusual within Lepidochitona but not unique. The supposed multiple slits in the sides of the valves did not stand up to scrutiny. Instead, intermediate valves of L. lioplax bore only a single slit on each side, in line with other Lepidochitona species. The original inference of multiple slits was an error due to the original specimen being still partially embedded in the surrounding matrix.

Lepidochitona lioplax is one of the earliest known representatives of its genus but its exact significance is obscure. It has been suggested as a direct ancestor of the modern subgenus Spongioradsia but this, again, was based on the supposed slits in the intermediate valves that Dell'Angelo et al. refuted. To know how L. lioplax connects to the big picture of Lepidochitona evolution, we would probably need a better picture of Lepidochitona evolution overall.

REFERENCES

Dell'Angelo, B., A. Bonfitto & M. Taviani. 2011. Chitons (Polyplacophora) from Paleogene strata in western Washington State, U.S.A. Journal of Paleontology 85 (5): 936–954.

Smith, A. G. 1960. Amphineura. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1: Mollusca—General Features, Scaphopoda, Amphineura, Monoplacophora, Gastropoda—General Features, Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I41–I76. Geological Society of America, and University of Kansas Press.