Field of Science

Narona decaptyx: A Fossil Vampire

13.5 mm long specimen of Narona decaptyx, from Landau et al. (2012).

Narona decaptyx was described by Brown & Pilsbry (1911) from a single small, fusiform fossil shell, 11 mm in length, from the Gatun Formation of Panama, north of Panama City. They regarded the formation as probably Oligocene in age but Landau et al. (2012) later referred N. decaptyx to the upper Miocene. Until it's redescription by the latter, this species was only known from Brown & Pilsbry's original holotype; Landau et al. described further material from the Bocas del Toro region to the west of the original locality. Both the sites from which N. decaptyx are known are on the Caribbean coast of Panama.

Narona decaptyx is a member of the Cancellariidae, the nutmeg snails. Cancellariids are one of the smaller families of the great neogastropod radiation, the group that also includes such forms as whelks and cone shells. They generally have a more or less developed sculpture of criss-crossing spiral and axial ribs; the latticed pattern this produces is formally referred to as 'cancellate' and provides the source of the family's name. The most distinctive feature of Cancellariidae is their radula, a slender ribbon of long, flexible teeth arranged in a single row. How this radula functioned was long a mystery. Dissections of the gut of cancellariids failed to find any trace of solid food, and it was suggested they may be adapted to some form of suctorial feeding. Some authors suggested that cancellariids might feed by slurping up micro-organisms. Then, in the 1980s, one species of cancellariid Cancellaria cooperi was observed feeding on sleeping electric rays. The snail would cut incisions in the ray's skin, presumably with its radula, before inserting its proboscis to slurp up the fish's blood (O'Sullivan et al. 1987). Other cancellariids have been observed feeding on fluids from other invertebrates such as benthic molluscs or their egg masses.

Cancellaria cooperi feeding on an electric ray, copyright Clinton Bauder.

The genus Narona to which N. decaptyx belongs is now restricted to the north Pacific. In this respect, it is not unique. Cancellariids are poorly represented in the modern Caribbean fauna with only six species known from the sea's shallow waters but they were much more diverse there in N. decaptyx's time. However, following the rise of the isthmus of Panama, many cancellariid taxa once found widely in the tropical Americas became extinct for whatever reason on the eastern side of the divide. This happened regularly enough that the term 'paciphile' has been coined for referring to such taxa. A number of distinct waves of paciphile extinctions have been identified in the Caribbean cancellariid fossil record and they have been used to identify distinct chronological zones. Narona decaptyx became extinct as part of the GNPMU (Gatunian Neogene Paciphilic Molluscan Unit) 1 period. Other Narona species persisted in the Caribbean and Gulf of Mexico for longer, surviving into the Pliocene, but eventually they too succumbed to whatever dampened this family's prospects in the region.


Brown, A. P., & H. A. Pilsbry. 1911. Fauna of the Gatun Formation, Isthmus of Panama. Proceedings of the Academy of Natural Sciences of Philadelphia 63 (2): 336–373.

Landau, B., R. E. Petit & C. M. da Silva. 2012. The family Cancellariidae (Mollusca: Gastropoda) in the Neogene of the Bocas del Toro region, Panama, with the description of seven new species. Journal of Paleontology 86 (2): 311–339.

O'Sullivan, J. B., R. R. McConnaughey & M. E. Huber. 1987. A blood-sucking snail: the Cooper's nutmeg, Cancellaria cooperi Gabb, parasitizes the California electric ray, Torpedo californica Ayres. Biological Bulletin 172 (3): 362–366.

The Adrastini

Glyphonyx sp., copyright Mike Quinn.

For the subject of my next post, I drew the click beetle tribe Adrastini. Well, actually, I drew the tribe Synaptini but dibs on that name was originally called by a family of sea cucumbers so it seems that 'Adrastini' should be the tribe's proper name. I described click beetles, and the nature of their click, in an earlier post.

The Adrastini are one of those groups of animals for which there seems to be little known to discuss other than their general morphology. The more typical click beetles tend to be fairly uniform in their general appearance and are often not that easy to distinguish. Adrastins belong to the subfamily Elaterinae and resemble other elaterines in their deflexed mouthparts, arcuate prosternum, open mesocoxal cavities and tarsal claws without basal setae. They differ from other elaterines in having serrate tarsal claws according to Stibick (1979). Mind you, another related group, the Melanotini, are supposed to be distinguished by their pectinate claws and I'm not entirely sure what the difference between 'serrate' and 'pectinate' is supposed to be in this context.

The Adrastini are widespread though they seem to be absent from Australia. Several genera are recognised; one of these, Glyphonyx, is distinctly larger than the rest and includes about half the tribe's known species. As far as I know, the larva has never been described for any member of this group, so what they are doing ecologically remains a largely unknown quantity.


Stibick, J. N. L. 1979. Classification of the Elateridae (Coleoptera). Relationships and classification of the subfamilies and tribes. Pacific Insects 20 (2–3): 145–186.

The Stilt Bug Neides tipularius

Image copyright Janet Graham.

This is Neides tipularius, a widespread bug in the western part of the Palaearctic region. It feeds on a wide range of plants: I've seen references to it on grasses, on composites, or on chickweeds. It prefers drier regions such as coastal dunes or heaths.

Neides tipularius is a fairly typical member of the stilt bug family Berytidae. Berytids are more or less slender bugs in general but Neides is one of the more slender and long-legged ones. There are few other bugs with which a berytid could be confused; not only is there the wispy legginess to mark them, but berytids have distinctive long antennae with a short, spindle-shaped terminal segment forming a dark bobble at the end. Latreille (1802) did place N. tipularius in the genus Ploiaria, but that is now used for a group of small, long-legged assassin bugs with raptorial forelegs for catching prey.

Image copyright Sanja565658.

As with many other bugs, Neides tipularius exhibits polymorphism in wing development with flightless brachypters having narrower wings that only just reach the tip of the abdomen. Whether a given individual grows into a flying or flightless adult appears to be connected to the conditions under which they develop. Hot springs and summers have been noted to lead to increased numbers of macropterous adults.


Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 3. Familles naturelles des genres. F. Dufart: Paris.

Rust, Anyone?

At certain times of year, when the weather is warm, you may see patches of yellow or orange appear on plant leaves. It is often particularly notable on grass. These patches are known as rust and are the fruiting bodies of parasitic fungi. In some cases, they may be merely a nuisance or an eyesore. In other cases, their effects can be devastating. Rust fungi may cause enormous damage to commercial crops. One particularly nasty strain of the stem rust Puccinia graminis that goes by the label of TTKSK or Ug99 has been spreading through Africa and Asia since its discovery in Uganda in 1999, causing up to 100% losses in wheat crops where it hits. A similar strain of the same species was recently involved in outbreaks in southern Europe. And this rust can't just be covered over with a bit of bog.

Stem rust Puccinia graminis uredia on wheat, from the US Dept of Agriculture.

Puccinia is the largest genus of rusts with around 3000 known species (Liu & Hambleton 2010), infecting a wide range of host plants. Many rusts have complicated life cycles...or perhaps that should be 'insane'. Some of you may be aware that, until recently, mycologists (researchers of fungi) maintained a system of dual nomenclature that classified sexual and asexual forms of fungi separately, due to the difficulty in matching one to the other*. Rust fungi can have a life cycle involving a sexually reproducing stage and two different asexually reproducing stages on two different hosts, all of them distinct in appearance, so many rust fungal species could masquerade under no less than three distinct names! But then, some species might have simpler life cycles dropping one or more of the possible stages, and some might restrict their attentions to a single host. The difficulty of wrapping one's head around rust life cycles may perhaps best be conveyed by reproducing one paragraph from the review by Petersen (1974), which I invite you to look upon below in all its hideous hideousness:

*I believe that the botanical code of nomenclature was recently changed to no longer allow this set-up as a formal system, but I presume that it's going to take a long time to work that one through.

A complex system of nomenclature has been developed to quickly indicate the stages found in any particular life cycle in the rusts. While easily understood by students of the group with some experi- ence, the system at first appears bewildering. Those taxa which exhibit all five stages during their life history are called Euforms. They may be Heter-Eu- (infecting more than one host) or Aut-Eu- (occurring on a single host). In some rusts, the aecial stage is deleted, or the aecia and aeciospores are morphologically identical to uredia and uredospores, these organisms being termed Brachy-forms. All these forms are autoecious, thus enabling the "aut-" prefix to be dropped. For those organisms in which spermogonia and spermatia are missing, Maire used Cata- as a prefix, but this usage is rarely seen nowadays. When the uredial stage has been dropped, the organism is called an Opsis-form. This may be used as a prefix, such as Opsis- Gymnosporangium, or more commonly as a suffix, such as Gymno- sporangiopsis. Again, forms can be Heter-Opsis-, or Aut-Opsis-. If this life cycle also deleted spermogonia, it was dubbed Catopsis- by Maire. In more general terminology, rust fungi exhibiting chiefly teliospores (with or without spermogonia) are known as Micro-forms, but Maire again specified those which exhibited both telia and spermogonia as Hypo-forms. In these forms, the teliospores are normal in that they require a resting period before germination. In some taxa, teliospore-like propagules are produced which are lighter in color, exhibit thinner walls, and more obscure germ pores, and which require no resting period before germination, often germinat- ing in situ. These spores have been called leptospores, and the life cycle, otherwise identical to that of Micro-forms, is known as Lepto- form. Occasionally, only uredospores and teliospores are found (these sometimes are thought of as imperfect rusts in which other stages will hopefully be found), and these are called Hemi-forms. Finally, in some taxa the teliospores are cytologically similar to aeciospores, in which case the life cycle is called Endo-, the species with such structures often segregated in the genus Endophyllum.

Life cycle of stem rust Puccinia graminis, from US Dept of Agriculture.

A typical 'full' rust life cycle is the one gone through by stem rust, shown in the diagram above. Stem rust alternates between two hosts, grasses such as wheat (it also infects related species such as barley or rye) and barberry. Sexual reproduction occurs on barberry near the beginning of the growing season when haploid spores known as spermatia or pycniospores are produced from fruiting bodies called spermatogonia or pycnia. In Puccinia species, these spermatogonia are flask-shaped and tend to be evenly spaced across the host tissue; other rust fungi may produce more irregular and irregularly-spaced spermatogonia. At the sides of the flask's opening are protruding hyphae to which spermatia from other spermatogonia fuse. Now, in animals such as ourselves, fusion of sperm and ovum is usually immediately followed by fusion of their respective haploid nuclei to form the diploid daughter nucleus. In rusts, however, the haploid parent cells fuse but their nuclei do not. Instead, the daughter cell grows and divides as a dikaryotic organism with two nuclear lineages remaining associated but distinct in each cell. The dikaryotic mycelium produced from fusion of spermatium and receptive hypha gives rise to a fruiting body known as an aecium which in Puccinia is cup-shaped. The aecium produces its own spores that are shed to infect the alternate host, the grass, to which they gain access through the host's stomata. Germinating aeciospores grow into a mycelium that penetrates host cells, absorbing nutrients directly from the host cytoplasm. When the time comes for the next reproductive stage, the rust produces a compacted layer called a uredinium that gives rise to yet another spore type, urediniospores. Unlike aeciospores that travel from one host to another, urediniospores are able to re-infect the same host, giving rise to a new uredinial stage of the life cycle. This asexual sub-cycle continues indefinitely for as long as growing conditions remain good for the rust. When conditions deteriorate, the rust stops producing urediniospores and begins producing thick-walled teliospores that are able to persist through the cold winter. It is within the teliospores that the dikaryotic nuclei finally fuse, giving rise to daughter nuclei that then themselves undergo meiosis so the teliospore germinates at the beginning of the next season to release haploid basidiospores, that infect a barberry to begin the cycle anew.

Arum rust Puccinia sessilis aecia on leaf of Arum maculatum, copyright Velella.

Because of the need for two hosts in the life cycle, crop pests such as stem rust may potentially be controlled by eradicating the second host. However, first you have to know what to target. Stripe rust Puccinia striiformis is another significant pest of grass crops whose alternate host was not identified as barberry until 2010 (Jin et al. 2010). And in warmer climates where urediniospores can survive all year round, rusts may be able to persist asexually even without a suitable alternate host.


Jin, Y., L. J. Szabo & M. Carson. 2010. Century-old mystery of Puccinia striiformis life history solved with the identification of Berberis as an alternative host. Phytopathology 100: 432–435.

Liu, M., & S. Hambleton. 2010. Taxonomic study of stipe rust, Puccinia striiformis sensu lato, based on molecular and morphological evidence. Fungal Biology 114: 881–899.

Petersen, R. H. 1974. The rust fungus life cycle. Botanical Review 40 (4): 453–513.