Research Article |
Corresponding author: James Liebherr ( jkl5@cornell.edu ) Academic editor: Martin Husemann
© 2017 James Liebherr.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Liebherr JK (2017) Bryanites graeffii sp. n. (Coleoptera, Carabidae): museum rediscovery of a relict species from Samoa. Zoosystematics and Evolution 93(1): 1-11. https://doi.org/10.3897/zse.93.10802
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Bryanites graeffii sp. n. is described from Samoa based on a single male specimen collected between 1862–1870 that was recently discovered in the Muséum national d’Histoire naturelle, Paris. Cladistic analysis based on 127 morphological characters from 49 exemplars of the carabid beetle tribe Platynini in the Austral-Pacific region, places the new species as adelphotaxon to Bryanites samoaensis Valentine, type species of the genus Bryanites Valentine, 1987. Bryanites comprises, along with Vitagonum Moore, 1998 of Fiji and Ctenognathus Fairmaire, 1843 of New Zealand, a clade that diverged early in the evolutionary history of Pacific platynine Carabidae. Bryanites graeffii exhibits very large body size among taxa of Platynini—16.2 mm standardized body length—with the genus characterized by vestigial flight wings and metathoracic apomorphies that are associated with flight-wing loss. Along with Blackburnia Sharp, 1878 of Hawaii, the origins of Bryanites, Vitagonum, and Ctenognathus are hypothesized to date to the Miocene, with their radiations beginning long before the origins of the geographically widespread, flight-capable species of Metacolpodes Jeannel, 1948 that colonized numerous island systems across the western Pacific. Given the numerous platynine taxa collected by extensive biotic surveys of Samoa during the first quarter of the 20th Century, the absence of any specimens of B. graeffii since the initial collection of the unique holotype prior to 1871 suggests that this species may be extinct. Such extirpation of large platynine carabid beetles has also been documented for Hawaii, where the time of extinction of seven Blackburnia species represented only by subfossil fragments coincides with the time of human colonization and attendant introduction of the Pacific rat, Rattus exulans (Peale).
anthropogenic extinction, biogeography, brachyptery, Polynesia
It is undeniable that natural history museums represent invaluable and irreplaceable archives of biological diversity on Earth. Firstly these institutions serve as repositories for many millions of studied and described specimens: i.e. type specimens and associated subsequent collections of named species. Secondly museums also hold uncounted, unstudied specimens that have been collected and processed, but never adequately examined or understood by a taxonomic specialist. Predictably, examination of unidentified material collected long ago can produce surprising results, especially when the historical museum specimens represent the only evidence we have for existence of that particular species. For example, two Samoan species of flying fox, genus Pteropus Brisson, 1762 (Chiroptera: Pteropodidae), are known only from museum specimens collected between 1839 and 1856 (
The specimen described in this contribution is a member of the carabid beetle tribe Platynini belonging to the genus Bryanites Valentine, 1987 (
This paper first traces the provenance of the newly described Samoan beetle specimen from its collection in nature to the present day. We cannot be certain why the specimen avoided description until now. But the documented timing of expeditions and subsequent taxonomic publications coupled with the temporal connections of the various taxonomists, and how the beetle could have passed from hand to hand, make a strong case for how a large carabid beetle from a tropical island could be ignored for well over a century to be rediscovered within a natural history museum. In order to be certain how best to classify the new species, cladistic analysis using morphological characters is used to phylogenetically place the species. After adding the new species to a little-known clade of Samoan Carabidae, the question regarding the fate of this lineage in nature is investigated, with parallels from the platynine carabid beetle fauna of the Hawaiian Islands suggesting a likely scenario for this species leading from the 19th to the 21st Century.
Taxonomic material. Specimens treated in this contribution were borrowed from the Muséum national d’Histoire naturelle, Paris (
Several taxa were added to complement the previous analysis. Colpodes kanak Fauvel (
Laboratory Techniques. Dissection protocols used throughout development of the present character matrix are detailed in
Character data. The cladistic analysis was based on 127 characters, 26 scored from the female reproductive tract and gonocoxae (i.e. ovipositor), 21 scored from male genitalic structures, and 80 derived from external anatomical structures (Suppl. material
Cladistic methods. The character matrix was developed in WinClada (
Provenance. The specimen rediscovered in the Paris Museum (Fig.
Cladistic Analysis. Subjecting the taxon-character matrix to Nona (
Strict consensus cladogram of 49 taxa of Pacific platynine carabid beetles. Type species, where included, indicated by asterisks. See text for further explanation of cladistic analysis. Distributional areas of species include: As, Asia; Au, Australia; F, Fiji; HI, Hawaiian Islands; I, India including Sri Lanka; Jp, Japan; Jv, Java; NC, New Caledonia; NG, New Guinea; NZ, New Zealand; Ph, Philippine Islands; R, Rapa; Sa, Samoa; So, Solomon Islands; Sunda, Sunda Islands; T, Tahiti and Society Islands; V, Vanuatu.
Other relationships inherent in the tree are very similar to those discussed in
Taxonomic challenges remain regarding monophyletic classification of species in the genera Colpodes and Notagonum, and these must be addressed via a more comprehensive and informative phylogenetic analysis, such as those that include DNA-molecular characters (e.g.
Bryanites samoaensis Valentine (by original designation).
These beetles can be diagnosed from other Pacific platynine taxa by the much reduced subapical sinuation of the elytra, with the elytral margins straight to convex near the apex (Fig.
Beetles of all three Bryanites species are brachypterous, with the wing rudiments narrow and elongate stenopterous straps, the length of the rudiments more than 4× the rudiment breadth. Beetle size is moderate to large, ranging from 11.7 mm in B. barri (measurement of Barr 1987) to 16.2 mm in B. graeffii.
1. | Beetles of moderate size, standardized body length 11.7–12.5 mm; pronotum quadrisetose both lateral and basal setae present; parascutellar seta present | 2 |
– | Larger beetles, standardized body length 16.2 mm; pronotum bisetose, only basal seta present both sides; parascutellar seta absent | B. graeffii sp. n. |
2. | Third elytral interval with 6 setae along length, the anterior seta associated with the third stria, the trailing five setae associated with the second stria; elytral basal groove meeting lateral elytral depression at right angle; pronotum without any evident laterobasal depressions, at most a slight depression near hind margin (left side of holotype) | B. samoaensis Valentine |
– | Third elytral interval with 3 setae along length, the anterior seta associated with the third stria, the posterior two setae associated with the second stria; elytral basal groove meeting lateral elytral depression at acute angle; pronotum with broad, shallow linear laterobasal depressions extended from hind angles toward center of pronotal disc | B. barri Valentine |
Besides the very large size of this beetle—standardized body length 16.2 mm—the elytral and pronotal setation are diagnostic. The elytra lack the parascutellar seta and any dorsal elytral setae, though both subapical and apical setae are present in the seventh stria near the rounded sutural apex. The pronotum has only the basal seta present, with this seta’s position 0.14× the median pronotal length anterad a transverse line drawn across the median pronotal base. The pronotal lateral marginal depression is broad and upraised to a smooth, unbeaded margin. The prosternal process is flat between the procoxae, with four to five setae each side approaching the process apex. Cuticular microsculpture is particularly well developed, with the frons and clypeus bearing distinct, upraised isodiametric sculpticells, and the vertex covered with more transverse, though equally well-developed sculpticells. The pronotal and elytral discs are covered with very small transverse sculpticells, the sculpticells’ small size giving the surface a velvety or velour-like reflection.
Head broad, robust, ocular ratio 1.61; antennae elongate, as long as distance from antennal socket to elytral midlength; scape stout, maximal breadth 0.5× distance from basal constriction to apex; antennomeres 2–3 apparently glabrous, but sparsely covered with very short microsetae, an apical ring of setae on antennomere 3; antennomere 4 apparently glabrous in basal ¼ of length, though also with very short microsetae, remainder of antennomere and antennomeres 5–11 pilose with darker brunneous, glabrous longitudinal ridge on each anterior and posterior surface; frontal grooves very shallow, ending posteriorly anterad the anterior supraorbital seta; posterior supraorbital setal position behind posterior margin of eye and 3× as far from eye margin as anterior seta; frons and clypeus not demarked by suture, surfaces convex, continuous, only three very shallow transverse wrinkles medially at position of frontoclypeal suture; labral anterior margin straight, only slightly incurved medially; mentum tooth broad, apex flattened medially, mentum setae positioned posterad curved mentum margin each side of midline; submentum with two setae each side. Pronotum broad, maximal width 1.08× median length; lateral margins only slightly incurved anterad rounded hind angles; broadly longitudinal laterobasal depressions joined by well-defined transverse depression anterad basal convexity; median longitudinal impression very finely incised, absent on basal convexity, continuous to beaded front margin; front angles projected anteriorly, their apex tightly rounded; lateral marginal depression of equal breadth from midlength to front angles, about twice as broad in basal half of pronotum; proepisternum smooth, proepimeron very narrow. Elytra flattened overall, sutural intervals upraised at suture in apical half of length; elytral apex evenly rounded; elytral striae finely incised, completely smooth, the intervening intervals nearly flat; humeri narrowed, with elytral basal groove meeting lateral depression at obtuse-angulate juncture, i.e., the humerus; seventh stria with two setae near strial apex; eighth striae with 33–37 lateral elytral setae more or less continuously distributed along elytral length, but with greater intersetal distances near midlength. Legs gracile, elongate; profemur with eight setae along anteroventral margin; mesofemur with 8–11 setae along posteroventral margin; metacoxa bisetose, two lateral setae present anteriorly and posteriorly, median seta absent; metafemur with eight setae along posteroventral margin, three setae on anterodorsal surface near apex from 0.7–0.8× femoral length; metatarsomeres 1–3 convex dorsally, without evident inner or outer dorsal sulci; metatarsomere 4 lobate apically, length of outer apical lobe 0.4× median tarsomere length, length of inner lobe 0.25× median length; tarsomeres 14 with two parallel longitudinal rows of elongate ventrolateral setae each side of a central space, the setae of inner rows each side about half as long as setae of outer rows; metatarsomere 5 apparently with eight ventrolateral setae, equal in length to tarsomere depth, set in two longitudinal rows (several setae broken off). The pronotum and elytra of the type specimen are covered with a varnish-like substance that can be scraped off with difficulty (Fig.
Aedeagal median lobe elongate, evenly narrowed from midlength to apex extended 4.0× its dorsoventral breadth beyond the apex of the ostial opening (Fig.
Holotype male (
The species epithet honors Dr. Eduard Graeffe, zoologist and naturalist from Zurich, Switzerland who collected the type specimen while working in Samoa from 1862–1870 (Clunie & Snow 1986). The species epithet is formed from Gräffe converted to Latin iconography, and without the terminal letter. This formation is consistent with several other honorific epithets for Eduard Gräffe; e.g. Epeira graeffii Keyserling (Arachnida: Araneidae), now combined with Phonographa Simon, 1894, Lamellidoris graeffii Bergh (Nudibranchia: Dorididae), and Pachycephala pectoralis graeffii Hartlaub (Aves: Pachycephalidae).
Based upon the results of the cladistic analysis, Colpodes kanak Fauvel is newly combined with the genus Notagonum Darlington: Notagonum kanak (Fauvel) comb. n. (Suppl. material
The results of the cladistic analysis succeed in the goal of placing the new species as a member of a Samoan lineage, Bryanites, that exhibits a close biogeographic relationship to the Fijian relict, Vitagonum (
The question of whether any or all of the Bryanites species are extinct is necessarily open ended. Nevertheless, examination of the circumstances of their collections taken within the context of other biological surveys of Samoa paint a grim picture as to the possibility of their continued existence in nature. The single specimen of Bryanites graeffii was collected prior to 1871 by a naturalist principally interested in birds and marine invertebrates (
The Bishop Museum’s Whitney South Seas Expedition of 1924, including E. H. Bryan, Jr. as entomologist, also visited Samoa (
Given these various lines of data, it seems unlikely that Bryanites beetles currently exist in nature. Only through the perspicuous collecting by E. H. Bryan, Jr. and the passing of his two specimens to J. Manson Valentine could the first two species of this genus be described (
The curators at the Bishop Museum, Honolulu, and the Muséum national d’Histoire naturelle, Paris have graciously let me work in their collections over the years with free access to specimens and with a minimum of distractions. I thank the following for their support of my curatorial and collection-based research efforts: James Boone, Neal Evenhuis, Scott E. Miller, Gordon Nishida, G. Allan Samuelson (Bishop Museum); Thierry Deuve, Jean Menier, Helène Perrin, Azadeh Tagavian (Paris Museum). I thank Martin Baehr, Zoologische Staatssammlung München, for sharing his findings regarding species identities in the Notagonum marginellum-submetallicum-complex. The underlying research on Hawaiian platynine beetles was supported by National Science Foundation grants DEB-9208269, DEB-9806349, and DEB-0315504.
Taxonomic checklist
Data type: Adobe PDF file
Explanation note: Taxa included in cladistic analysis taxonomically placing Bryanites graeffii sp. n. are listed along with their taxonomic authorities.
Computer file for cladistic analysis
Data type: Adobe PDF file
Explanation note: The NONA format data file that supports the cladistic analysis of Bryanites and Pacific Platynini is provided for export to a plain text editor.