Paper 2 Flashcards
discussion
main points/question
- Describing a New Species: To describe and illustrate a novel fungal species, Gibellula attenboroughii, which infects cave-dwelling, orb-weaving spiders of the subfamily Metainae (Tetragnathidae) in the British Isles.
- Understanding Ecology and Behavior: To investigate and discuss the ecology of Gibellula attenboroughii, including whether infected spiders exhibit behavioral changes similar to those reported for zombie ants, where they move to exposed situations before death.
- Clarifying Systematics: To address the hidden diversity of the genus Gibellula in the British Isles, based on fungarium records and literature searches, and to transfer two spider pathogens previously assigned to the genus Torrubiella to the genus Gibellula: Gibellula albolanata and G. aranicida.
- Phylogenetic Analysis: To conduct morphological and phylogenetic analyses to confirm the taxonomic novelty of the Gibellula species found on cave spiders and to determine its distinctiveness from other accepted species.
- Historical Overview: To provide a historical overview of the entomopathogenic mycobiota of the British Isles, focusing on records of Gibellula and related fungi on spiders.
- Ecological Significance: To discuss the ecological significance of araneopathogenic fungi and their potential impact on spider populations.
conclusions
The main conclusions of the research described in the paper are:
- Identification of a New Species: The study successfully identified and described a new fungal species, Gibellula attenboroughii, that infects cave-dwelling orb-weaving spiders in the British Isles. Phylogenetic analysis confirmed its distinctiveness and relationship to other Gibellula species.
- Behavioral Manipulation: The research suggests that spiders infected with Gibellula attenboroughii exhibit behavioral changes, similar to those seen in zombie ants, where they move to exposed locations before dying, potentially aiding in fungal spore dispersal.
- Taxonomic Revisions: Two species, previously classified under Torrubiella (T. albolanata and T. aranicida), were reclassified and transferred to the Gibellula genus, based on their Granulomanus synasexual morphs, aligning with the one fungus-one name nomenclature.
- Hidden Diversity: The study highlights a previously underappreciated diversity of Gibellula species in the British Isles, indicating that more species remain to be discovered.
- Ecotypic Variation: Differences in the morphology of Gibellula attenboroughii on different spider hosts (Metellina merianae and Meta menardi) are likely due to ecotypic variation related to microclimates within cave systems and differences in spore dispersal strategies.
- Mycoparasites: Mycoparasites, including Nodulisporium-like isolates, were found on Gibellula-infected spiders, suggesting complex ecological interactions within cave systems.
- Ecological Impact: The research suggests that Gibellula fungi could have a significant impact on spider populations, warranting further study of their role in spider population dynamics and their potential metabolites.
figure 1
Figure 1 presents a maximum likelihood phylogenetic tree illustrating the relationships among spider-pathogenic hypocrealean fungi, specifically focusing on the genera Jenniferia, Hevansia, and Gibellula.
Here’s a breakdown:
- Phylogenetic Tree: It’s a visual representation of the evolutionary relationships among different fungal species based on a concatenated dataset of ITS, SSU, LSU, TEF, RPB1, and RPB2 gene sequences. This means that multiple genes were sequenced for each species, and the resulting data was combined to create a more robust and accurate tree.
- Clade Focus: The tree highlights a specific clade (a group of organisms evolved from a common ancestor) that contains the major spider pathogenic hypocrealean genera: Jenniferia, Hevansia, and Gibellula.
- Gibellula attenboroughii Highlight: The newly proposed species, Gibellula attenboroughii, is highlighted in bold, emphasizing its position within the Gibellula clade and its relationship to other species.
- Circular Phylogeny (Left): On the left side, a circular phylogeny represents the full dataset used in the study, encompassing the broader Cordycipitaceae family. This provides context for the focused view of the Jenniferia, Hevansia, and Gibellula clade.
- Purpose: The figure visually supports the taxonomic placement of Gibellula attenboroughii within the Gibellula genus and demonstrates its evolutionary relationship to other spider-pathogenic fungi. It uses molecular data to validate the morphological and ecological observations that led to the identification of this new species.
figure 2
Figure 2 depicts Gibellula attenboroughii, the holotype IMI 507230, on its orb-weaving spider host, Metellina merianae. Here’s a detailed description:
- A and B. On Spider Host: These images show the fungus on the spider after removal and drying. Image A shows the spider body completely covered by a dense, white mycelial mat. Image B shows that the mycelial mat becomes creamish yellow upon drying, and multiple synnemata are visible. The scale bars indicate 1 cm.
- C. Long Conidiophores: This image shows long conidiophores scattered along the lower part of a synnema. The scale bar is 50 µm.
- D. Short Conidiophores: This image shows short conidiophores densely clustered in the terminal part of the synnema. The scale bar is 50 µm.
- E and F. Spore Columns: These images show dense, white spore columns on the conidiophores. Image E shows these columns on short conidiophores at the apex of the synnema (scale bar: 100 µm), while image F shows them on long conidiophores at the base (scale bar: 25 µm).
In summary, Figure 2 provides a visual overview of the macroscopic and microscopic characteristics of Gibellula attenboroughii on its spider host, illustrating the distribution of synnemata, the arrangement of conidiophores, and the structure of the spore columns.
figure 3
Figure 3 illustrates the conidiophore morphology of Gibellula attenboroughii, specifically from the holotype IMI 507230. Here’s a breakdown:
- A. Synnema with Astipitate Conidiophores: This image shows a synnema with conidiophores clustered towards the apex, appearing almost astipitate (lacking a stalk). The scale bar is 40 µm.
- B and C. Conidiophores at Base: These images show conidiophores located towards the base of the synnema. They have long, roughened stipes (stalks) and short, smooth neck regions. The scale bars are 50 µm for B and 25 µm for C.
- D. Conidia: This image shows the conidia (spores) of the fungus. They are hyaline (translucent), smooth, ellipsoidal to fusoid in shape, and measure 4–6 × 1.5–2 µm. The scale bar is 10 µm.
In essence, Figure 3 provides a detailed microscopic view of the conidiophores of Gibellula attenboroughii, highlighting the differences in morphology between those at the apex and base of the synnema, and illustrating the characteristic shape and size of the conidia. It aids in the identification and characterization of this newly described species.
figure 4
Figure 4 illustrates the in vitro (culture) characteristics of Gibellula attenboroughii, specifically from the holotype IMI 507230. Here’s a breakdown:
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A and B. Colony Morphology:
- A: Shows the colony after 6 weeks on MEA (malt extract agar). It’s described as slow-growing (0.7–0.9 cm in diameter), white and stromatic (having a dense, compact structure). It turns creamish to pale brown, is raised centrally, often furrowed, and exhibits a brown diffusate around the periphery.
- B: Shows the colony after 6 weeks on PCA (potato-carrot agar). It’s slower growing than on MEA, dark cream in color with a greyish brown reverse.
- The scale bar for both A and B is 3 mm.
- C. Colony after 4 Months on MEA: This image shows the colony after 4 months on MEA. It has become feathery and irregular at the periphery (up to 3.0 cm in diameter) and is forming chains of small, hyaline chlamydospores. Additionally, short synnemata are occasionally developing centrally (indicated by the arrow). The scale bar is 1.5 mm.
- D. Detail of Synnema: This image provides a closer view of a synnema formed in culture. It shows the short conidiophores crowded at the tip (indicated by the short arrow) and the longer, scattered conidiophores at the base (indicated by the long arrow), similar to what is observed on the host. The scale bar is 60 µm.
In summary, Figure 4 illustrates the cultural characteristics of Gibellula attenboroughii, showing its growth rate, colony morphology on different media (MEA and PCA), and the formation of synnemata and chlamydospores in older cultures. It provides valuable information for identifying and characterizing the fungus in a laboratory setting.
figure 5
Figure 5 showcases Gibellula attenboroughii paratypes in situ (in their natural environment) on Metallina merianae spiders.
- A. Cave Ceiling, Tullybelcoo Ground Bridge: Shows the fungus on a cave ceiling in Tullybelcoo Ground Bridge, County Fermanagh, Northern Ireland. The scale bar is 1.5 mm.
- B. Whitefathers’ Caves: Shows the fungus in Whitefathers’ Caves, County Cavan, Republic of Ireland. The scale bar is 1.5 mm.
- C. On Moss, Lake Vyrnwy: Shows the fungus on moss at Lake Vyrnwy, Powys, Wales. This image is credited to D. McNeil. The scale bar is 1 mm.
The figure highlights the typical appearance of the fungus on its spider host in its natural environment. It shows densely-packed white to pale yellow synnemata. The figure emphasizes the diverse habitats where the fungus can be found, including cave ceilings and moss-covered surfaces, and the similar appearance of the fungus across these different locations.
figure 6
Figure 6 presents Gibellula attenboroughii paratypes on the orb-weaving spider Meta menardi.
- A. Paratype IMI 507601, in situ: This shows the paratype attached to a cave wall above the River Barran in Whitefathers’ Caves, County Cavan, Republic of Ireland. Multiple white synnemata cover the dorsal surface of the spider. The scale bar is 4 mm.
- B. After Drying: This shows the same paratype after drying. Multiple creamish synnemata are visible on the ventral abdomen. The scale bar is 3 mm.
- C. Paratype IMI 507603, after drying: This shows another paratype after drying. Note the free conidiophores on the legs and the naked head region with prominent eyes (indicated by the arrow). The scale bar is 3 mm.
- D. Paratype IMI 507602, after drying: This shows a paratype hanging from a thread above a river, displaying abundant synnematal production on both the dorsal and ventral surfaces. The scale bar is 3 mm.
In summary, Figure 6 shows the macroscopic appearance of Gibellula attenboroughii on Meta menardi, emphasizing the synnemata covering the spider’s body. It shows variations in synnematal density and distribution and shows a distinct appearance from the in situ images shown in Figure 5.
figure 7
Figure 7 details the micro-morphology of Gibellula attenboroughii on Meta menardi, specifically paratype IMI 507601.
- A. Detail of Upper Part of Synnema: This image shows the tapering apex of a synnema with densely-crowded, penicillioid conidiophores. The scale bar is 50 µm. It also refers the reader to compare this to Figure 2D, where the conidiophore arrangement may appear different.
- B. Conidiophores: This image shows individual conidiophores with short, lightly-roughened stipes and simple penicillioid heads. The scale bar is 10 µm.
- C. Detail of Conidiophore Head: A close-up of a conidiophore head is shown, featuring a prominent, smooth neck region. The scale bar is 10 µm.
- D. Conidial Chain: Shows a chain of conidia (spores). The scale bar is 10 µm.
In essence, Figure 7 provides a microscopic view of Gibellula attenboroughii on Meta menardi, highlighting the structure of the synnema, the morphology of the conidiophores and their heads, and the arrangement of conidia in chains. The figure is essential for understanding the reproductive structures of the fungus on this specific host.
figure 8
Figure 8 illustrates the in vitro (culture) characteristics and micro-morphology of Gibellula attenboroughii paratype IMI 507601, which was isolated from Meta menardi.
- A. Colony with Aspergilliform Conidiophores: This image shows a colony after 3 months on PCA, with aspergilliform conidiophores produced directly from the mycelium. The scale bar is 3 mm.
- B. Chlamydospore-like Structures: This shows chlamydospore-like structures and verrucose (warty) hyphae from the subiculum (the underlying mass of hyphae). The scale bar is 15 µm.
- C. Aspergilliform Conidiophore: An aspergilliform conidiophore arising directly from the mycelium is shown. The scale bar is 15 µm.
- D. Conidiogenous Heads: Shows both aspergilliform and penicillioid conidiogenous heads on the mycelium. The scale bar is 15 µm.
In summary, Figure 8 shows the appearance of Gibellula attenboroughii in culture, including the colony morphology, the formation of chlamydospore-like structures, and the presence of both aspergilliform and penicillioid conidiophores.
figure 9
Figure 9 provides habitat context and presents the Gibellula attenboroughii paratype IMI 507598, found on Meta menardi.
- A. Whitefathers’ Caves - Dark Zone: This image shows the dark zone above the River Barran inside Whitefathers’ Caves, County Cavan, Republic of Ireland. This illustrates the typical habitat of the spider and fungus.
- B. Entrance and Twilight Zone: This image shows the entrance and twilight zone of the caves, providing broader environmental context.
- C. Infected Spider in situ: This image depicts an infected spider on the cave ceiling. The spider shows early infection with immature synnemata on a compact, white subiculum. This specimen was found immediately above the figure in the center of the image. The scale bar is 0.5 mm.
- D. Dried Specimen: This image showcases the dried specimen, revealing a creamish-yellow subiculum covering the ventral abdomen of the spider. The scale bar is 0.25 mm.
Essentially, Figure 9 combines environmental context with close-up views of the fungus on its host within its natural cave habitat. It illustrates the specific location where infected spiders were found (the dark zone) and demonstrates the appearance of the fungus both in situ and after drying.
figure 10
Figure 10 presents Gibellula attenboroughii in situ on orb spiders, and illustrates mycoparasite macro-morphology.
- A. On Orb Spiders: This image shows Gibellula attenboroughii on two different orb spider species, Metellina merianae (left, short arrow) and Meta menardi (right, long arrow), on a cave ceiling in Whitefathers’ Caves. The image highlights the differences in synnematal morphology between the two hosts.
- B. Mycoparasite Overgrowth: At the same site as A, this image shows a Meta menardi specimen completely overgrown by a Nodulisporium-like mycoparasite, forming a ‘slimy blob’.
- C. Dried Specimens: Shows dried specimens, with the larger Meta menardi on the left and the smaller Metellina merianae on the right.
- D. Mycoparasite in Culture: This shows the mycoparasite after one month on PCA, forming slimy colonies. The scale bar is 10 mm.
In summary, Figure 10 illustrates both the morphological differences of Gibellula attenboroughii on different hosts and shows how the fungus itself can be parasitized by other fungi, adding another layer of complexity to the ecological interactions.
figure 11
Figure 11 presents images related to the new Gibellula combinations proposed in the paper. Specifically, it shows specimens and illustrations relevant to Gibellula albolanata and Gibellula aranicida.
- A. Gibellula albolanata comb. nov. (Type of Torrubiella albolanata): Shows the red-legged spider, Gongylidium rufipes, with the yellow ascomata (indicated by the arrow) embedded in a white subiculum. The specimen is from fen sedge in Norfolk, 1942. The scale bar is 1 mm.
- B. Type illustration of Isaria cuneispora: This shows the Granulomanus synasexual morph of G. albolanata on Gnaphosa lucifuga, from France (Boudier, 1887).
- C. Gibellula aranicida comb. nov. (labelled as Torrubiella aranicida): This shows a specimen from Yorkshire, 1936, with yellow-orange ascomata scattered on the spider legs and body. The scale bar is 2 mm.
- D. Type illustration of Torrubiella aranicida: This shows the ascomata on Gnaphosa lucifuga, France (Boudier, 1885).
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E, F. Gibellula aranicida on Coelotes atropos:
- E: Shows a dried fungarium specimen collected by G. Lyon in Devon, 2023. Note the scattered yellow ascomata. The scale bar is 2 mm.
- F: This is a close-up image taken in situ, displaying white or pellucid ascomata on the spider’s legs (image credit: G. Lyon).
In short, Figure 11 provides visual support for the taxonomic reclassifications proposed in the paper, showcasing the key morphological features of the species transferred to Gibellula.
New Species Discovery:
The paper describes Gibellula attenboroughii, a novel fungal species infecting cave-dwelling orb-weaving spiders in the British Isles.
Behavioral Manipulation (Zombie Spider)
It suggests that G. attenboroughii may induce behavioral changes in its spider hosts, causing them to move to exposed locations before death, similar to zombie ants.
Taxonomic Revisions:
Two species previously classified as Torrubiella albolanata and Torrubiella aranicida, were transferred to the Gibellula genus based on the “one fungus-one name” principle. This was based on their Granulomanus synasexual morphs.
Hidden Diversity:
The study reveals that the Gibellula genus in the British Isles is more diverse than previously recognized, suggesting that additional species may be present.
Ecotypic Variation:
The paper highlights morphological differences in G. attenboroughii depending on the spider host, suggesting ecotypic variation driven by microclimatic conditions within cave systems.
Mycoparasites
The presence of mycoparasites on Gibellula-infected spiders adds another layer of complexity to the ecological interactions within cave ecosystems.
Habitat and Distribution:
The study provides insights into the specific habitats of Gibellula species in the British Isles, particularly cave systems and upland lake areas.
Historical Context:
The paper provides a historical overview of research on entomopathogenic fungi in the British Isles, recognizing the contributions of earlier mycologists like Tom Petch.
Methodology:
The research employed a combination of field collection, morphological examination, DNA sequencing, and phylogenetic analysis to characterize the new species and revise the taxonomy of related fungi.
