Moss' account of another snake-mimic: Madoryx plutonius

In my last post, I shared Moss' description of snake-mimicry in Hemeroplanes triptolemus caterpillars. In the same publication - The Sphingidae of Para, Brazil - he describes another spectacular caterpillar he encountered - Madoryx plutonius (he refers to it at M. pluto). This is another sphingid which also appears to mimic a snake. Moss supposed that these two species were close relatives, and this is now supported with molecular genetics as well (Kawahara et al 2009). Interestingly though, despite being related species the colour patterns and defensive behaviours in each species are so distinct that I suspect that they evolved independently. One of my current projects involves identifying how many times eyespots and snake mimicry have evolved independently in Sphingidae.

For now, I'd just like to showcase this amazing caterpillar and Moss' description of its defensive behaviour (see below). These photos of Madoryx plutonius are again taken from the Janzen and Hallwachs database. The specimens were collected in Costa Rica as part of the ongoing inventory project within the Área de Conservación Guanacaste run by Dan Janzen and Winnie Hallwachs.

317. Madoryx pluto. (Plate 6.) [p. 394]

The larva in its final in star, if the championship among frauds be already won by the Leucorhawpha species [Moss is referring to H. triptolemus], nevertheless runs them closely, and takes a very high second place in the perfect success of those devices resorted to in first simulating the living stalk or stem of its food-plant, and then by endeavouring to terrorize one into the belief that one is gazing at an open-mouthed snake with red jaws and a couple of fierce, blue- black eyes' set immediately above them.

Final instar Madoryx plutonius caterpillar (at rest)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

Final instar Madoryx plutonius caterpillar (defensive posture)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

Final instar Madoryx plutonius caterpillar (defensive posture)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

This particular effect is produced entirely on the dorsal area by the larva lowering its head towards its legs, puffing out its thoracic segments (not laterally this time), and exhibiting these wonderfully brilliant touches of external ornament which at all other times when the caterpillar is sleeping or even when it is eating or in motion are entirely concealed within the interstices of its segments, and looks a perfect stick of a light brown coloration. Though I secured two photos, to take its portrait as a snake in pencil and paint was an exceedingly difficult task, for it would never maintain the attitude for a sufficient length of time, and soon got tired of even repeating the hoax for the edification of my much-impressed friends.

Final instar Madoryx plutonius caterpillar (at rest)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

Final instar Madoryx plutonius caterpillar (in defensive posture)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

Final instar Madoryx plutonius caterpillar (in defensive posture)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

Final instar Madoryx plutonius caterpillar (recovering to rest posture)
Photo of specimen 95-SRNP-4624 from Janzen and Hallwachs database.

Related posts:

• Moss' account of Hemeroplanes larvae in Para
• Possibly the best known eyespot caterpillar: Hemeroplanes sp. (Sphingidae)

References:

Kawahara, A. Y., Mignault, A.A., Regier, J.C., Kitching, I.J. and Mitter, C.M. (2009) Phylogeny and biogeography of hawkmoths (Lepidoptera: Sphingidae): evidence from five nuclear genes. PLoS ONE 4(5): e5719. doi:10.1371/journal.pone.0005719

Moss AM. 1920. The Sphingidae of Para, Brazil. Novitates Zool. 27:333–424.

Moss' account of Hemerplanes larvae in Para

When you are starting to dig through the literature for a new research topic, it is often very rewarding to go back and actually read the earliest accounts you can find - especially for biologists. This is because early naturalists wrote beautifully and often provide very detailed, thorough descriptions. Sometimes you are even rewarded with really amazing engravings, paintings, or sketches of the specimens they observed or collected. I also feel that going back to these early works gives you a great historical perspective on the work you are doing. Occasionally you even feel a kind of connection to these writers when you are studying the same phenomena or specimens they witnessed (or collected) 50-100 years ago (perhaps even earlier). Many biologists have this experience when they read Darwin's On the Origin of Species. If not, there are many other places to look.

Some really detailed work on South American hawkmoths, and their larvae, was done by a man named Rev. Arthur Miles Moss, M.A., F.Z.S., F.E.S., British Chaplain of Pará. His work is interesting to me because of his detailed descriptions of many caterpillars with eyespots, and their close relatives. I haven't been able to find much information on the man himself except for what is posted on the British Natural History Museum website which I have reproduced below:

Arthur Miles-Moss (1873-1948)
Born in Liverpool, Arthur Miles-Moss studied at Trinity College, Cambridge. He was ordained deacon in the Church of England in 1895 and then priest the following year. In 1897 he travelled to South America and from 1907 to 1910 he lived in Peru before moving to Pará in Brazil, 100 miles south of the mouth of the river Amazon where he stayed until 1945. In 1912 he built the Pará Anglican Church. His parish covered a vast area of Brazil and he was known as the vicar of the largest parish in the world. 

In his spare time he began a detailed study of the insects of the region and amassed a large collection of butterflies and moths (Lepidoptera). He also reared and made detailed drawings of the caterpillars and pupae. A talented artist, he also painted many land- and seascapes, some of which he exhibited at the Royal Academy, London.

Moss put his skills as an accomplished artist to work painting the countless caterpillars and pupae that he reared in his spare time. The Natural History Museum has a collection of his manuscripts, drawings and photographs. Many of these are watercolour paintings or drawings of caterpillars annotated with various observations he made when rearing the larvae. Their collection also hold ~25000 preserved specimens from the caterpillars that he reared. Here is a sample of his artwork:

Arthur Miles-Moss (1873-1948)
Drawing of the larval stage of the Saturniid moth (Leucanella nyctimene)
Watercolour on paper, 78 x 165 mm.

I would love to visit this collection. I have seen a few other pieces of his work from the parts of it that he published, but I'm sure that there are still many of his paintings and detailed notes that for now remain out of sight. The two notable publications I have been interested in are "On the Sphingidae of Peru" from 1912 and "Sphingidae of Para, Brazil" written in 1920. They have detailed descriptions of many hawkmoth caterpillars - some of which have eyespots - and include notes on their behaviour.

I have written before about the extraordinary snake-mimic caterpillars of Hemeroplanes sp. here. Moss also collected and wrote about this species. To give you an idea of how spectacular these caterpillars can be here is a photo:

Hemeroplanes triptolemus (Sphingidae)
Photo of specimen 87-SRNP-1156 from the Janzen and Hallwachs database.

Moss (1920) gives a really nice description of this caterpillar (Moss refers to it as Leucorhampha triptolemus) and includes notes on its intricate defensive behaviour. I have reproduced his description of the mimetic and behavioural features below and added photos of a live specimen to illustrate the features he is describing:

312. Leucorhampha triptolemus. (Plates 6 & 9.) 

[p. 391-392]

The description which I now quote was written in November 1916 for the larva of ornatus, but as it applies equally well for triptolemus and must be regarded as doing double duty, I prefer to insert it here. The larva is quite one of the most remarkable of living creatures that I have ever seen, a perfect Aaron's rod, combining in the most novel and striking way the principles of protective resemblance with an aggressive snake-mimicry. When at rest as an adult caterpillar, it hangs by two pairs of claspers in the vertical from the stem of its food-plant, and appears to be nothing but a broken branch covered with a creamy white lichen. A strange black chequered dorsal design, with a gradual intensification of the grey on certain segments completes the deception. 

Hemeroplanes triptolemus (Sphingidae)
Photo of specimen 03-SRNP-11366 from the Janzen and Hallwachs database.

The wonder, however, is if possible exceeded when, on being disturbed, this marvel of creative evolution endeavours once more to deceive by turning into a snake, and in quite a different way to that adopted by Xylophanes or even by its fairly close relative Madoryx pluto. 

Aside: The relationship between Madoryx and Hemeroplanes is still being worked out. It looks as though they are indeed related but evolved snake mimicry independently - that is to say that it is unlikely that both species mimic snakes simply because they share a common snake-mimicking ancestor.

Though this wonderful transformation wants to be seen in life to be fully appreciated, I may explain briefly that the effect is produced by the creature turning itself over and exhibiting its ventral area, which is adorned by a broad band of dark olive-green with the three anterior sets of claspers completely withdrawn and scarcely visible.

Hemeroplanes triptolemus (Sphingidae)
Photo of specimen 03-SRNP-11366 from the Janzen and Hallwachs database.

The thoracic segments, which are always swollen, become puffed out laterally to an exaggerated extent; a pair of black eyes on segment 4, hitherto concealed and situated behind the now recumbent and wholly inconspicuous legs, open out;

Hemeroplanes triptolemus (Sphingidae)
Photo of specimen 03-SRNP-11366 from the Janzen and Hallwachs database.

the cheeks appear to be adorned by yellow scales with black edges ; and the fraudulent notion that one is beholding merely the head and neck of a formidable, if small, snake is carried to a nicety by the rigidity of the curve adopted.

Hemeroplanes triptolemus (Sphingidae)
Photo of specimen 03-SRNP-11366 from the Janzen and Hallwachs database.

Then, as if to mesmerize, a swaying side-to-side motion is kept up for an appreciable number of seconds, before the creature, seeming to realize that an attack is no further contemplated, gradually closes its false eyes and relapses once more into diurnal slumbers. That this mimicry of the fore-part of a small serpent, if mimicry it be, for it is hard to give it any other name, should be chiefly produced on the ventral surface, a feature peculiar in itself, and that every detail should so contribute in perfecting the deception, is altogether remarkable.

Related posts:

• Possible the best known eyespot caterpillar: Hemeroplanes sp. (Sphingidae)
• This post includes a video clip of the behaviour described above

References:

Moss AM. 1912. On the Sphingidae of Peru. Trans Zool Soc Lond. 20:73–135.
Moss AM. 1920. The Sphingidae of Para, Brazil. Novitates Zool. 27:333–424.