Research Article |
Corresponding author: Dmitry A. Sidorov ( biospeorossica@gmail.com ) Academic editor: Charles Oliver Coleman
© 2016 Dmitry A. Sidorov, Aron D. Katz, Steven J. Taylor, Mikhail V. Chertoprud.
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:
Sidorov DA, Katz AD, Taylor SJ, Chertoprud MV (2016) A reassessment of the phylogenetic utility of genus-level morphological characters in the family Bogidiellidae (Crustacea, Amphipoda), with description of a new species of Eobogidiella Karaman, 1981. ZooKeys 610: 23-43. https://doi.org/10.3897/zookeys.610.9100
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Bogidiellidae is the most diverse and cosmopolitan family of stygobiotic amphipods, and inhabits a variety of subterranean biotopes, especially interstitial habitats. While the family is characterized by considerable sexual dimorphism, this dimorphism has adversely affected our understanding of the systematics of the group. Most species have restricted geographic ranges and occur in difficult to sample habitats, so it is common for individual species descriptions to be based on a single sex. In this work we revisit an analysis of morphological characters in an attempt to clarify their phylogenetic utility in resolving taxonomic relationships among genera by introducing a new species, two additional characters, and phylogenetic statistical support values. Eobogidiella venkataramani sp. n., from a spring fed brook in the Shirawati River basin along the escarpment of the Western Ghats (Karnataka, India) differs from the only known congener, Eobogidiella purmamarcensis, from Argentina, in the structure of mouthparts, the shape and ornamentation on gnathopods and characters of the telson. Our phylogenetic analyses indicate that the available morphological characters are not sufficient to resolve phylogenetic relationships within Bogidiellidae, thus these characters alone cannot be used to determine the phylogenetic placement ofE. venkataramani sp. n. within the family. Nevertheless, E. venkataramani sp. n. shares diagnostic characters with Eobogidiella, supporting placement of the new species in this genus. Our findings point towards a critical need to resolve relationships within the family using molecular approaches, along with the development of a suite of additional morphological characters for Bogidiellidae. This is the third species of Bogidiellidae from southern India.
Biodiversity, Subterranean fauna, Karnataka, Taxonomy, Phylogenetic analysis
The family Bogidiellidae Hertzog, 1936 has an intriguing history of study that shaped the systematics of the group (e.g.,
Only two Bogidiellidae species are known from India: Bogidiella indica
Below we describe Eobogidiella venkataramani sp. n. from a spring-fed freshwater habitat in southwest India and evaluate the phylogenetic utility of the available morphological characters (
A sample containing the stygobiont (one specimen) was collected in December 2008 from a spring-fed brook in the state of Karnataka in southwest India (Figs
Body length was recorded while holding the specimen straight and measuring the distance along the dorsal side of the body from the base of the first antenna to the base of the telson using an ocular micrometer in a Lomo MBS-9 dissecting microscope. Appendages were drawn using a Carl Zeiss NU-2 compound microscope equipped with a drawing device as described in
Due to improper storage, the specimen was entirely dry upon initial examination. We followed the method described by
The term “palmar angle” of the gnathopod propodi refers to the angle formed at the end of the palm and beginning of the posterior margin or the point at which the tip of the dactylus closes on the propodus (
To investigate the phylogenetic utility of the available morphological characters we used a revised version of the morphological data matrix used by
We used the Bogidiellidaesensu lato in our analysis, including Artesiidae, as its acceptance as a distinct family has been questioned (
Following
FEFU Zoological Museum of the Far East Federal University, Vladivostok
To investigate the phylogenetic utility of the available morphological characters and to determine the placement of our new species among the bogidiellids, we reevaluated the relationships within the family, adding new taxa and characters to the morphology matrix of
Maximum parsimony strict consensus tree of genera and selected species of Bogidiellidae, ordered analysis. Numbers above branches are Decay/Bremer indices and numbers below branches are bootstrap followed by jackknife support values. Support values less than 50% not displayed. Scale bars indicate number of character state changes. See Suppl. material
Maximum parsimony strict consensus tree of genera and selected species of Bogidiellidae, unordered analysis. Numbers above branches are Decay/Bremer indices and numbers below branches are bootstrap followed by jackknife support values. Support values less than 50% not displayed. Scale bars indicate number of character state changes. See Suppl. material
The two additional characters (i.e., the presence or absence of a coxal endite on the maxilliped, and the morphology of coxa 5) were added to the matrix of
The above analyses revealed that the available morphological characters provide no phylogenetic utility in resolving generic relationships within the Bogidiellidaesensu lato, thus the available morphological characters do not allow us to establish the phylogenetic placement of the new species. Therefore, the resulting phylogenies (Figs
Species distributions and selected morphological characters from for E. purmamarcensis, I. daccordii, I. sarawacensis, B. indica, B. totakura, and the new species. Characters listed in the table represent all morphological characters from Koenemann & Holsinger (1999) that are variable among presented taxa. Bold character states indicate that the state is shared with the new species.
Characters | Eobogidiella venkataramani sp. n. | Eobogidiella purmamarcensis (Grosso & Ringuelet, 1979) | Indogidiella daccordii (Ruffo, 1994) | Indogidiella sarawacensis (Stock, 1983) |
Bogidiella
indica
|
Bogidiella
totakura
|
---|---|---|---|---|---|---|
Distribution | India | Argentina | Phillipines | Borneo | India | India |
Modifications of the outer ramus in male pleopod 1 | absent | ? | absent | absent | absent | ? |
Modifications of the outer ramus in male pleopod 2 | absent | ? | absent | absent | absent | ? |
Number of outer ramus segments in pleopods 1-3 | 3 | 3 | 3 | 3 | 3 | 3 or 4 |
Inner rami of pleopods 1-3 | uniarticulate, reduced | uniarticulate, reduced | uniarticulate, reduced | uniarticulate, reduced | absent | absent |
Modifications in male uropod 1 | present | ? | present | present | present | ? |
Modifications in male uropod 2 | present | ? | present | present | absent | ? |
Dagger-shaped rami in male uropod 1 | absent | ? | absent | absent | absent | ? |
Dagger-shaped rami in male uropod 2 | absent | ? | absent | absent | absent | ? |
Gills | pleopods 3-6 | ? | ? | pleopods 4-6 | pleopods 2-6 | pleopods 4-6 |
Number of segments in flagellum of antenna 2 | 5 | 5 | 5 | 6 | 5 | 5 |
Number of segments in accessory flagellum | 1 | 2 | 3 | 3 | 1 | 3 |
Number of palp segments in maxilla 1 | 1 | 1 | 2 | 2 | 2 | 2 |
Number of setae on inner lobe of maxilla 1 | 2 | 3 | 2 | 2 | 4 | 0 |
Number of spines on outer lobe of maxilla 1 | 7 | 7 | 7 | 7 | 6 | 6 |
Mandibular molar | non-triturative | triturative | triturative | triturative | non-triturative | “semi-triturative” |
Number of apical spines of telson | 0 | 1 | 1 | 2 | 1 | 0 |
Number of subapical spines of telson | 2 | 3 | 0 | 0 | 0 | 1 |
syn.: Bogidiella (Eobogidiella) G.
Bogidiella (Eobogidiella) purmamarcensis Grosso & Ringuelet, 1979, (by original designation).
Habitus typical of a stygomorphic bogidiellid, combining a number of features found in other genera of this family.
Primary characters: maxilla 1 with vestigial, single-segmented, symmetrical palps; pleopods 1–3 with single-segmented, reduced inner rami.
Secondary characteristics: ventral surface of pereonites 2–7 bearing sternal humps; coxal gills on pereopods 3–6; antenna 1 with reduced, single-segmented, minute accessory flagellum; mandibles with tiny, vestigial molars with 2 short spines and 1 plumose seta; maxilliped lacking coxal endite; apparent sexual dimorphism (spines on uropods 1 and 2 modified).
Spring fed swamp in the upper reaches of a small logged brook (14.218667°N; 74.821667°E) in the Shirawati River basin, altitude above sea level 550 m, Western Ghats, Karnataka, India.
Holotype specimen. INDIA: probable ♂, 6.5 mm, X43794/Cr-1621-FEFU, vicinity of Jog Falls, Karnataka state, collected 5 Dec. 2008 by M.V. Chertoprud. Deposited in the Zoological Museum of the Far East Federal University, Vladivostok (FEFU).
Accompanying fauna: Goerodes sp. (Trichoptera: Lepidostomatidae), Isca sp. (Ephemeroptera: Leptophlebiidae), Phanoperla sp. (Plecoptera: Perlidae), Macromyia sp. (Odonata: Corduliidae), and many terrestrial leeches (Hirudinida) on the banks.
The specific epithet honors the former Director of Zoological Survey of India, Dr. K. Venkataraman, whose assistance was pivotal in the early stages of this research.
X43794/Cr-1621-FEFU. General body morphology (Figs
Unknown.
Unknown, but modified spines on uropods 1 and 2 probably represent a male-specific trait.
Eobogidiella venkataramani sp. n. dwells in a spring-fed brook habitat located on the flat bottom of a small valley in the rainforest. The biotope is a small trickling swampy stream 1–3 m wide and 0–0.05 m deep, without flow, water temperature +22 °C, and a substrate comprised of wet litter, detritus, stones, clay. Known only from type locality.
Eobogidiella venkataramani sp. n. is distinguished from E. purmamarcensis by the following characteristics (characteristics of the latter in parentheses): antenna 2 reaching 75% of antenna 1 length (about 50%); accessory flagellum comprised of 1 article (2 articles); molar vestigial, non-triturative (developed, triturative); mandibular palp article 3 with 3 setae on apex (1 seta); maxilla 1 inner plate with 2 setae (3 setae); maxilla 2 plates broad (narrow); maxilliped palp article 2 narrow (very broad); lenticular organs absent (present); telson with apical margin convex (with excavation apically).
The only other species in this genus, E. purmamarcensis was described by
In spite of our decision assign the new species to Eobogidiella, weak phylogenetic support for generic concepts and relationships within the family leaves us with reservations regarding this placement. The highly disparate known geographic distributions of Eobogidiella venkataramani sp. n. and E. purmamarcensis (India and Argentina, respectively) is suspicious, suggesting that some of their shared character states may be homoplasious. Furthermore, two important morphological characters may be misleading in their support of a close relationship between E. venkataramani sp. n. and E. purmamarcensis. First, the soft suture between the head and pereonite 1 described here for E. venkataramani sp. n. was not mentioned in the description of E. purmamarcensis (
Based on our reanalysis of
We thank to Mikhail Daneliya (University of Helsinki, Finland) and an anonymous reviewer for many helpful critical suggestions, and Dr. Ch. Oliver Coleman (Museum of Natural Science, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany) for editorial contributions which have improved this paper.
Morphological character matrix
Data type: NEXUS file
Explanation note: NEXUS file including character matrix for Bogidiellidae, Artesiidae and Kergueleniolidae used in analysis..
Figure S1
Data type: TIF file
Explanation note: Ordered bootstrap and jackknife consensus tree. Numbers below branches are bootstrap followed by jackknife support values.
Figure S2
Data type: TIF file
Explanation note: Unordered bootstrap and jackknife consensus tree. Numbers below branches are bootstrap followed by jackknife support values.