A major work on the scorpion fauna of Papua New Guinea with the descritpion of 16 new species in the genus Hormurus

 

Papua New Guinea is a large island in the Pacific and a treasure chest when it comes to biodiversity. The scorpion fauna of the island is not well known. In an extensive study, Lionel Monod and his research group studied the scorpions in the family Hormuridae in Paua New Guinea and 16 new species in the genus Hormurus Thorell, 1876 are described. 

Hormurus ancylolobus Monod & Prendini, 2023
Hormurus araiaspathe Monod & Prendini, 2023
Hormurus barai Monod, Iova & Prendini, 2023
Hormurus cameroni Monod, Austin & Prendini, 2023
Hormurus hypseloscolus Monod & Prendini, 2023
Hormurus krausi Monod & Prendini, 2023
Hormurus maiwa Monod & Prendini, 2023
Hormurus menapi Monod & Prendini, 2023
Hormurus muyua Monod & Prendini, 2023
Hormurus oyatabu Monod & Prendini, 2023
Hormurus oyawaka Monod & Prendini, 2023
Hormurus sibonai Monod & Prendini, 2023
Hormurus slapcinskyi Monod & Prendini, 2023
Hormurus sporacanthophorus Monod & Prendini, 2023
Hormurus tagula Monod & Prendini, 2023
Hormurus yela Monod & Prendini, 2023

Hormurus papuanus Kraepelin, 1914 is redescribed. This species was not previously listed in The Scorpion Files and is now added to the species list.

See abstract or article for further details about this study.

Abstract:
New Guinea is the largest Pacific island, and the world’s second largest, with a land area of about 785,000 km². Located north of Australia, the island was gradually shaped since the Eocene by the geologically recent sequential accretion of several island arc systems onto the northern part of the Australian Craton. This complex geological history has resulted in a tremendous biological diversity with high rates of endemism. On the other hand, the rugged mountainous landscape and lack of infrastructure has hampered scientific research in the country and for the most part Papuan biotas remain thus far only superficially known. This is the case for scorpions of the genus Hormurus Thorell, 1876 (Hormuridae Laurie, 1896; Scorpiones C. L. Koch, 1837). Although they are the dominant scorpion group in Wallacea and Melanesia, only two species are currently recognized from New Guinea and its adjacent islands. A thorough revisionary study of the Hormurus material present in the scientific collections of various museums and of a large series of specimens more recently collected led to the discovery of 16 new species, i.e. Hormurus ancylolobus Monod & Prendini, sp. nov.; Hormurus araiaspathe Monod & Prendini, sp. nov.; Hormurus barai Monod, Iova & Prendini, sp. nov.; Hormurus cameroni Monod, Austin & Prendini, sp. nov.; Hormurus hypseloscolus Monod & Prendini, sp. nov.; Hormurus krausi Monod & Prendini, sp. nov.; Hormurus maiwa Monod & Prendini, sp. nov.; Hormurus menapi Monod & Prendini, sp. nov.; Hormurus muyua Monod & Prendini, sp. nov.; Hormurus oyatabu Monod & Prendini, sp. nov.; Hormurus oyawaka Monod & Prendini, sp. nov.; Hormurus sibonai Monod & Prendini, sp. nov.; Hormurus slapcinskyi Monod & Prendini, sp. nov.; Hormurus sporacanthophorus Monod & Prendini, sp. nov.; Hormurus tagula Monod & Prendini, sp. nov.; Hormurus yela Monod & Prendini, sp. nov. Fully illustrated descriptions of these new taxa are presented in the present contribution, as well as a redescription of Hormurus papuanus Kraepelin, 1914. Hormurus species are characterized by relatively few diagnostic external characters which hampers species differentiation. However, the unusual interspecific diversity of hemispermatophores observed in Papuan taxa partially alleviate this issue and enable reliable species discrimination. The position of the laminar hook is particularly variable and is correlated with the elongation of the female genital operculum which also shows an atypical diversity for the genus. This interdependence strongly suggests genital coevolution driven by a lock-and-key mechanism. This would be the first such case reported for the order Scorpiones Koch, 1837. Multivariate and geometric morphometric analyses were carried out to visually emphasize subtle interspecific differences in external morphology and hemispermatophore morphology. Additionally, the correlation between hemispermatophore laminar hook position and shape of the female genital operculum was assessed statistically and comments are provided concerning potential mechanisms underlying the coevolutionary process.

Reference:
Monod L, Lehmann-Graber C, Austin CC, Iova B, Prendini L. Atlas of Australasian hormurid scorpions. I. The genus Hormurus Thorell, 1876 in Papua New Guinea. Exceptional morphological diversity in male and female copulatory structures suggests genital coevolution. Rev Suisse Zool. 2023;130(Suppl.):1-243. [Open Access]

Thanks to Gerard Dupre for sending me this article!

Family Hormuridae

Increased predator exposure changes scorpion venom cocktail to become a more effective weapon

I just came across a very interesting article on phenotypic plasticity in scorpion venom. Scorpion venom is a cocktail of different toxins having different effects on different targets (e.g. one toxin is effective against invertebrates, another against mammals and a third against both). The matter in question in the current study is if scorpions are able to modify the ‘recipe’ of its venom cocktail, and thereby optimizing the fitness benefits of its costly venom, in different environments exhibiting differences in densities and types of predators and prey.

The Australian species Hormurus waigiensis (Gervais, 1843) (Hormuridae) was used in this study.

And interestingly, the results showed that simulated predator exposure appeared to decrease relative production of strong invertebrate toxins, while generally increasing the production of a section of the venom profile with activity towards mammalian cells. Put in other words, it seems that at least in Liocheles waigensis, increased interactions with a potential predator will cause the venom to become more effective (dangerous) against the predator and less effective against invertebrate prey.

So don't provoke your scorpions! This may make them more dangerous ;)

Abstract:
Animals embedded between trophic levels must simultaneously balance pressures to deter predators and acquire resources. Venomous animals may use venom toxins to mediate both pressures, and thus changes in this balance may alter the composition of venoms. Basic theory suggests that greater exposure to a predator should induce a larger proportion of defensive venom components relative to offensive venom components, while increases in arms races with prey will elicit the reverse. Alternatively, reducing the need for venom expenditure for food acquisition, for example because of an increase in scavenging, may reduce the production of offensive venom components. Here, we investigated changes in scorpion venom composition using a mesocosm experiment where we manipulated scorpions’ exposure to a surrogate vertebrate predator and live and dead prey. After six weeks, scorpions exposed to surrogate predators exhibited significantly different venom chemistry compared with naive scorpions. This change included a relative increase in some compounds toxic to vertebrate cells and a relative decrease in some compounds effective against their invertebrate prey. Our findings provide, to our knowledge, the first evidence for adaptive plasticity in venom composition. These changes in venom composition may increase the stability of food webs involving venomous animals.

Reference:
Gangur AN, Smout M, Liddell MJ, Seymour JE, Wilson D, Northfield TD. Changes in predator exposure, but not in diet, induce phenotypic plasticity in scorpion venom. Proc Biol Sci. 2017;284(1863). [Subscription required for full text]

Hormuridae reinstalled after study on the evolution, biogeography and phylogeny of Indo-Pacific taxa

Indo-Pacific hormurid scorpion phylogeny from one of the two new studies on hormurid scorpions.

Lionel Monod and Lorenzo Prendini have recently published a major study on the evolution, biogeography and phylogeny of Indo-Pacific scorpions belonging to several genera previously placed in Hemiscorpiidae. This is a complicated study and I recommend to read the paper to get all details concerning the conclusions listed below.

Another paper by Monod, Harvey and Prendini on hormurid scorpions was published in the end of last year. This paper actually preceded the Monod & Prendini paper in content, and I have therefor not written about it until now, when the latter paper is published. In the first paper three new species of Hormurus are described and the evolution of burrowing behavior in the reinstalled family Hormuridae is discussed.

Main conclusions:

Family Hormuridae Laurie, 1896 is elevated to family rank after being a subfamily in Hemiscorpiidae.

The genera Hormiops Fage, 1933 and Hormurus Thorell, 1876, previously placed in synonymy with Liocheles Sundevall, 1833, are reinstated as valid genera. See Scorpion Files family page for list of species which are included in the reinstalled genera.

Genera Cheloctonus Pocock, 1892, Chiromachetes Pocock, 1899, Chiromachus Pocock, 1893, Hadogenes Kraepelin, 1894, Hormiops Fage, 1933, Hormurus Thorell, 1876, Iomachus Pocock, 1893, Liocheles Sundevall, 1833, Opisthacanthus Peters, 1861, Palaeocheloctonus Lourenco, 1996 and Tibetiomachus are included in Hormuridae.

The family Hemiscorpiidae includes now only the genus Hemiscorpius Peters, 1861.

Based on the conclusions in the current paper, I have chosen to reinstall the family Heteroscorpionidae Kraepelin, 1905 in The Scorpion Files and moved the genus Heteroscorpion Birula, 1903 from Hemiscorpiidae to Heteroscorpionidae. See familiy pages (links below) for more details.

The following new species are described from Australia:

Hormurus ischnoryctes Monod & Prendini, 2013
Hormurus macrochela Monod, 2013
Hormurus ochyroscapter Monod, 2013

Hormurus longimanus (Locket, 1995) is reinstated as the valid name for this species and the replacement name, Liocheles extensus Locket, 1997 is placed in synonymy.

Abstract 1:
Scorpions previously assigned to the genus Liocheles Sundevall, 1883, of the family Hormuridae Laurie, 1896, are widely distributed in the tropical forests of the Indo-Pacific region. Revisionary systematics of these poorly known scorpions has revealed a tremendous diversity of species. As part of an ongoing investigation, the first analysis of Indo-Pacific hormurid scorpion phylogeny based on morphological data scored for all currently recognized species of Hormiops Fage, 1933, Hormurus Thorell, 1876, and Liocheles, is presented. The taxonomy of these scorpions is reassessed and their biogeography reinterpreted in the light of the phylogeny. Phylogenetic, morphological, and distributional data support the revalidation of Hormiops and Hormurus, previously synonymized with Liocheles. The phylogeny indicates that the Australasian hormurids are more closely related to the Afrotropical and Neotropical hormurids than to the Indian hormurids, as previously proposed, refuting the “out-of-India” origin of Asian hormurids. A recent paleogeographical hypothesis, the “Eurogondwana model”, is supported instead. According to this hypothesis, hormurid scorpions colonized Laurasia from Africa via the Apulia microplate (Europa terrane) in the Cretaceous, subsequently colonized the Australo-Papuan archipelago in the early-mid Cenozoic, and then went extinct in the Northern Hemisphere during the second half of the Cenozoic. These results suggest that, contrary to the traditional paradigm, dispersal and extinction may affect spatial and temporal biotic distributions as much as vicariance, even in animals with limited vagility, such as scorpions.

Abstract 2:
Three new species from the semi-arid ecosystems of Queensland, Australia, are described in the present contribution: Hormurus ischnoryctes n. spec., Hormurus macrochela n. spec., Hormurus ochyroscapter n. spec. Additionally, the discovery of the first female specimens of Hormurus longimanus (Locket, 1995) from the Northern Territory of Australia, as well as additional diagnostic characters and locality records for this species, warranted its redescription. Hormurus longimanus (Locket, 1995) is reinstated as the valid name for this species and the replacement name, Liocheles extensus Locket, 1997 placed in synonymy. Unlike most species of Hormurus and of the closely related genera, Hormiops Fage, 1933 and Liocheles Sundevall, 1883, which inhabit humid tropical ecosystems (evergreen forests), the four Australian species treated here inhabit seasonally dry (monsoon) habitats, and two of these (H. ischnoryctes and H. ochyroscapter) are the first fossorial hormurids to be recorded in Australia, and the first fossorial species of Hormurus to be described. The four species treated here appear to be relicts of an old hygrophilous lineage that sustained a major adaptive radiation during the late Tertiary aridification of the continent. Endemism and conservation issues coneerning these phylogenetically valuable species are discussed in the context of high sensitivity to habitat disturbance and high risk of extinction of stenotopic species.

Reference 1:
Monod L, Prendini L. Evidence for Eurogondwana: The roles of dispersal, extinction and vicariance in the evolution and biogeography of Indo-Pacific Hormuridae (Scorpiones: Scorpionoidea). Cladistics. 2014;In Press. [Subscription required for full text]

Reference 2:
Monod L, Harvey MS, Prendini L. Stenotopic Hormurus Thorell, 1876 scorpions from the monsoon ecosystems of northern Australia, with a discussion on the evolution of burrowing behaviour in Hormuridae Laurie, 1896. Rev Suisse Zool. 2013 Jun;120(2):281-346.

Family Hormuridae
Family Hemiscorpiidae
Family Heteroscorpionidae