Island hoppers: Integrative taxonomic revision of Hogna wolf spiders (Araneae, Lycosidae) endemic to the Madeira islands with description of a new species

Abstract

Because of their ability for aerial dispersal using silk and preference for open habitats, many wolf spiders are formidable colonisers. Pioneering arachnologists were already aware of the large and colourful wolf spiders in the Madeira archipelago, currently included in the genus Hogna Simon, 1885. The origins were investigated and species boundaries of Madeiran Hogna examined by integrating target-gene and morphological information. A multi-locus phylogenetic analysis of a thorough sampling across wolf-spider diversity suggested a single origin of Madeiran endemics, albeit with low support. Divergence time estimation traced back their origin to the late Miocene, a time of major global cooling that drove the expansion of grasslands and the associated fauna. Morphological examination of types and newly collected material revealed a new species, hereby described as H.isambertoi Crespo, sp. nov. Additionally, H.blackwalli is revalidated and three new synonymies are proposed, namely H.biscoitoi Wunderlich, 1992, junior synonym of H.insularum Kulczynski, 1899, H.schmitzi Wunderlich, 1992, junior synonym of H.maderiana (Walckenaer, 1837), and Arctosamaderana Roewer, 1960 junior synonym of H.ferox (Lucas, 1838). Species delimitation analyses of mitochondrial and nuclear markers provided additional support for morphological delineations. The species pair H.insularum and H.maderiana, however, constituted an exception: the lack of exclusive haplotypes in the examined markers, along with the discovery of intermediate forms, pointed to hybridisation between these two species as reported in other congeneric species on islands. Finally, the conservation status of the species is discussed and candidates for immediate conservation efforts are identified.

Keywords: Endangered species; Lycosinae; Macaronesia; island radiation; morphological polymorphism; species delimitation.

Figure 1.

Map of the Macaronesia and the Madeira archipelago (adapted from Borges et al. 2008, with authors’ permission).

Figure 2.

Best maximum likelihood tree of Lycosinae, inferred with IQTREE2 after selecting the best partition scheme and evolutionary models. Nodes are split in three sections, representing the different methods. Support on nodes should be read as follows: black: ML ultrafast bootstrap and BI posterior probability ≥ 0.95, MP Jackknife ≥ 0.7; grey: ML Ultrafast Bootstrap and BI posterior probability < 0.95, MP Jackknife < 0.7; white: unrecovered node.

Figure 3.

Ultrametric tree for the COI obtained with BEAST using a coalescent (constant population growth) prior to apply the GMYC model. Only unique sequences included. Support on nodes should be read as follows: black: BI posterior probability ≥ 0.95; grey: BI posterior probability < 0.95. Species delimitations based on alternative approaches are indicated with boxes besides the terminal labels.

Figure 4.

COI haplotype (upper) and ITS-2 allele (lower) networks inferred under statistical parsimony (0.95 probability). Pie size proportional to number of individuals which exhibited the same haplotype/alleles. White circles represent missing haplotypes/alleles. Colours correspond to islands (colour codes in upper box). For the COI haplotypes only the network (3) including H.insularum / H.maderiana haplotypes showed (each remaining nominal species were resolved as independent networks). ITS-2 alleles boxed per species, except for H.insularum / H.maderiana. Haplotype/allele labels for H.insularum in bold and italics, H.maderiana in condensed bold and italics, not assigned in light italics (see lower box legend).

Figure 5.

Species tree for the Madeiran Hogna including two outgroups. Values on nodes are estimated divergence times in millions of years (my). Dots on nodes indicate BI posterior probability >0.95. Bars correspond to the 95%HPD of the time estimates.

Figure 6.

HognablackwalliA–C male (CRBALC0718): A left male pedipalp, ventral B detail of the median apophysis, anteroventral CSEM image, right male pedipalp, ventral D, E female (CRBALC0516): D epigyne, ventral (white arrow points to an indentation that may be helpful for diagnosis) E vulva, dorsal. Abbreviations, male pedipalp: AT – anterior point, C – cymbium, E – embolus, P – palea, R – ridge, T – tegulum, TA – terminal apophysis, TgA – tegular apophysis, VS – ventral spur. Abbreviations, female genitalia: D – diverticulum, H – epigynal hoods, MS – median septum, S – spermatheca. Scale bars: 0.5 mm (A, D, E); 0.2 mm (B, C).

Figure 7.

Photograph of H.blackwalli. Female specimen, recently dead, in captivity. Photograph credit Emídio Machado.

Figure 8.

Distribution of H.blackwalli. Circles: present records; black triangles: revised records from literature; white triangles: unconfirmed records from literature.

Figure 9.

Hognaheeri female (CRBALC0501): A epigyne, ventral B vulva, dorsal. Abbreviations, female genitalia: D – diverticulum, H – epigynal hoods, MS – median septum, S – spermatheca. Scale bars: 0.2 mm.

Figure 10.

Photograph of H.heeri. Female specimen in captivity. Photograph credit Emídio Machado.

Figure 11.

Distribution of H.heeri. Circles: present records; black triangles: revised records from literature; white triangles: unconfirmed records from literature.

Figure 12.

Hognaingens female (CRBALC0591): A epigyne, ventral B vulva, dorsal. Abbreviations, female genitalia: H – epigynal hoods, MS – median septum, S – spermatheca. Scale bars: 0.5 mm.

Figure 13.

Photograph of H.ingens. Female specimen in the field. Photograph credit Pedro Cardoso.

Figure 14.

Distribution of H.ingens. Black circles: present records; white triangle: unconfirmed record from literature.

Figure 15.

Hognainsularum, male pedipalps A male from Porto Santo (CRBALC0310), left pedipalp, ventral B male from Deserta Grande (CRBALC0305), left pedipalp, ventral C male from Bugio (CRBALC0015), left pedipalp, ventral D detail of the median apophysis of male from Deserta Grande (CRBALC0305), anteroventral ESEM image, right male pedipalp, male from Porto Santo (CRBALC0310), ventral F idem, retroventral. Abbreviations, male pedipalp: AT – anterior point, C – cymbium, E – embolus, P – palea, R – ridge, T – tegulum, TA – terminal apophysis, TgA – tegular apophysis, VS – ventral spur. Scale bars: 0.5 mm (A, B, C); 0.2 mm (D).

Figure 16.

Hognainsularum, female genitalia A, B female from Bugio (CRBALC0301): A epigynum, ventral B vulva, dorsal C, D female from Deserta Grande (CRBALC0308): C epigynum, ventral D vulva, dorsal E, F female from Madeira (CRBALC0597): E epigynum, ventral F vulva, dorsal G, H female from Porto Santo (CRBALC0300): G epigynum, ventral H vulva, dorsal. Abbreviations, female genitalia: D – diverticulum, H – epigynal hoods, MS – median septum, S – spermatheca. Scale bars: 0.2 mm.

Figure 17.

Distribution of H.insularum. Circles: present records; black triangles: revised records from literature; white triangles: unconfirmed records from literature.

Figure 18.

Hognaisambertoi sp. nov. A–C male (SMF): A left male palp, ventral B detail of the median apophysis, anteroventral CSEM image, right male palp, ventral D, E female (SMF): D epigynum, ventral E vulva, dorsal. Abbreviations, male palp: C – cymbium, E – embolus, MA – median apophysis, P – palea, T – tegulum, TA – terminal apophysis. Abbreviations, female genitalia: D – diverticulum, H – epigynal hoods, MS – median septum, S – spermatheca. Scale bars: 0.5 mm (A); 0.2 mm (B–E).

Figure 19.

Hognaisambertoi sp. nov. A male habitus, dorsal (SMF) B female habitus, dorsal (SMF). Scale bars: 1 mm.

Figure 20.

Distribution of H.isambertoi sp. nov. Circles: present records; black triangle: revised record from literature.

Figure 21.

HognamaderianaA–D male (CRBALC0734): A left male palp, ventral (white arrow points to a tegular concavity that may be helpful for diagnosis) B detail of the median apophysis, anteroventral CSEM image, right male palp, ventral D idem, retroventral E, F female (CRBALC0717): E epigynum, ventral F vulva, dorsal. Abbreviations, male pedipalp: AT – apical point, C – cymbium, E – embolus, P – palea, R – ridge, T – tegulum, TA – terminal apophysis, TgA – tegular apophysis, VS – ventral spur. Abbreviations, female genitalia: D – diverticulum, H – epigynal hoods, MS – median septum, S – spermatheca. Scale bars: 0.5 mm (A, B, E, F); 0.2 mm (C, D).

Figure 22.

Photograph of H.maderiana. Female specimen in the field. Photograph credit Pedro Cardoso.

Figure 23.

Distribution of H.maderiana. Black circles: present records; dotted circles: records from only leg samples; black triangles: revised records from literature; white triangles: unconfirmed records from literature.

Figure 24.

Hognanonannulata male (CRBALC0701): A left male pedipalp, ventral B detail of the median apophysis, anteroventral CSEM image, right male pedipalp, ventral. Abbreviations, male pedipalp: AT – apical point, C – cymbium, E – embolus, P – palea, R – ridge, T – tegulum, TA – terminal apophysis, TgA – tegular apophysis, VS – ventral spur. Scale bars: 0.5 mm (A); 0.2 mm (B, C).

Figure 25.

Distribution of H.nonannulata. Black circle: present record; white triangle: unconfirmed record from literature.

Figure 26.

Plate with photographs of the lateral view of the leg I for easily diagnosable species.

Figure 27.

Plate with photographs of the lateral view of the leg I for the complex of H.maderiana, H.insularum and their intermediate forms.

Figure 28.

Unidentified male specimens belonging to the H.maderiana / H.insularum complex from Porto Santo. Left male pedipalps, ventral A CRBALC0328 B CRBALC0345. Scale bar: 0.5 mm (A).

Figure 29.

Unidentified female specimens belonging to the H.maderiana / H.insularum complex from Porto Santo. Female genitalia A, B CRBALC0329 A epigyne, ventral B vulva, dorsal C, D CRBALC0346 C epigyne, ventral D vulva, dorsal. Scale bar: 0.5 mm (A).