Gustavo Hormiga Ruth Weintraub Professor of Biology Systematics and Evolutionary Biology of Spiders Department of Biological Sciences George Washington University 2023 G Street. NW Washington, D.C. 20052 421 Lisner Hall (office); 405 Bell Hall (lab) Tel. Lab: (202) 994-0302 Tel. Office: (202) 994-1095 Tel. Secretary: (202) 994-6090 Fax: (202) 994-6100 E-Mail: hormiga@gwu.edu Link to: Hormiga Lab

B.Sc. (Universidad de Barcelona, 1985), M.S., Ph.D. (University of Maryland at College Park, 1992, 1995).

The research in my laboratory focuses on the systematics and evolutionary biology of spiders, with emphasis on orbweavers and their close relatives (Orbiculariae). Most of the species-level systematic work in my lab addresses three spider lineages: the sheet weaving family Linyphiidae and Pimoidae, and the orb weaving families Tetragnathidae and Mysmenidae. We use morphological, molecular and behavioral characters to reconstruct the phylogenetic relationships of our study organisms, to tackle questions that span from species level problems to interrelationships of families. I am also interested in applying phylogenetic results to more general questions in evolutionary biology such as the evolution of sexual size dimorphism in orbweaving spiders (Hormiga et al., 2000) or the patterns of insular diversification and colonization in the Hawaiian archipelago (Hormiga et al., 2003). This work highlights the importance of reconstructing the history of evolutionary changes for addressing comparative questions. For example, the results of our research show that the extensively studied "male dwarfism" of nephiline spiders (Tetragnathidae), when placed in a phylogenetic context , is in fact a case of female gigantism.

Click on the following links to read more about some of our current projects:

Assembling the Tree of Life: Phylogeny of Spiders

PEET: Systematics and Monography of Araneoid Spiders

PBI: Goblin Spider Project

PANCODING: Panamanian Arthropods barcoding Initiative

Click here for the complete list of publications:

Dimitrov, D., L. Lopardo, G. Giribet, M. A. Arnedo, F. Álvarez-Padilla and G. Hormiga. 2012. Tangled in a sparse spider web: single origin of orb weavers and their spinning work unravelled by denser taxonomic sampling. Proceedings of the Royal Society B. 279 (1732):1341-1350. (doi:10.1098/rspb.2011.2011 )

Lopardo, L., G. Giribet and G. Hormiga. 2011. Morphology to the rescue: Molecular data and the signal of morphological characters in combined phylogenetic analyses—A case study from mysmenid spiders (Araneae, Mysmenidae), with comments on the evolution of web architecture. Cladistics 27, 278-330 (cover article). (doi:10.1111/j.1096-0031.2010.00332.x)

Dimitrov, D. and G. Hormiga. 2011. An extraordinary new genus of spiders from Western Australia with an expanded hypothesis on the phylogeny of Tetragnathidae (Araneae). Zoological Journal of the Linnean Society, 161: 735-768. (doi:10.1111/j.1096-3642.2010.00662.x)

Álvarez-Padilla, F. and G. Hormiga. 2011. Morphological and phylogenetic atlas of the orbweaving spider family Tetragnathidae (Araneae: Araneoidea). Zoological Journal of the Linnean Society 162(4): 713-880.

Tu, L., and G. Hormiga. 2011. Phylogenetic analysis and revision of the linyphiid spider genus Solenysa (Araneae: Linyphiidae: Erigoninae). Zoological Journal of the Linnean Society 161, 484–530. (doi:10.1111/j.1096-3642.2010.00640.x)

Michalik, P. and G. Hormiga. 2010. Ultrastructure of the spermatozoa in the spider genus Pimoa – new evidence for the monophyly of Pimoidae plus Linyphiidae (Arachnida: Araneae). American Museum Novitates 3682: 1-17.

Dimitrov D., Hormiga G. 2010. Mr.Darwin’s mysterious spider: On the type species of the genus Leucauge White, 1841 (Tetragnathidae, Araneae). ZOOTAXA 2396:19–36.

Tu, L., and G. Hormiga. 2010. The female genitalic morphology of “micronetine” spiders (Araneae, Linyphiidae). Genetica (DOI 10.1007/s10709-009-9368-9).

Benjamin, S., and G. Hormiga. 2009. Phylogenetic placement of the enigmatic genus Labullinyphia Van Helsdingen, 1985, with redescription of Labullinyphia tersa (Simon, 1894) from Sri Lanka (Araneae: Linyphiidae). Contributions to Natural History 12: 161-181.

Dimitrov, D., Benjamin, S., and G. Hormiga. 2009. A revised phylogenetic analysis for the genus Clitaetra Simon, 1889 (Araneoidea, Nephilidae) with the first description of the male of the Sri Lankan species Clitaetra thisbe Simon, 1903. Bulletin of the Museum of Comparative Zoology 159(6): 301-323. (doi:10.3099/0027-4100-159.6.301).

Arnedo, M.A., G. Hormiga, and N. Scharff. 2009. Higher level phylogenetics of linyphiid spiders (Araneae, Linyphiidae) based on morphological and molecular evidence. Cladistics 25: 231-262. Download PDF

Álvarez-Padilla F., Dimitrov D., Giribet G., Hormiga G. 2009. Phylogenetic relationships of the spider family Tetragnathidae (Araneae, Araneoidea) based on morphological and DNA sequence data. Cladistics 25:109-146. (doi: 10.1111/j.1096-0031.2008.00242.x)

Tu, L., and G. Hormiga. 2009. The female genitalic morphology of “micronetine” spiders (Araneae, Linyphiidae). Genetica (DOI 10.1007/s10709-009-9368-9).

Arnedo, M.A., G. Hormiga, and N. Scharff. 2009. Higher level phylogenetics of linyphiid spiders (Araneae, Linyphiidae) based on morphological and molecular evidence. Cladistics 25: 231-262.

Álvarez-Padilla F., Dimitrov D., Giribet G., Hormiga G. 2009. Phylogenetic relationships of the spider family Tetragnathidae (Araneae, Araneoidea) based on morphological and DNA sequence data. Cladistics 25:109-146. (doi: 10.1111/j.1096-0031.2008.00242.x)

Santos, A.J., M. O. Gonzaga, and G. Hormiga. 2009. Notes on two problematic eastern Asian species of the spider genus Oecobius (Araneae: Oecobiidae, Linyphiidae). Journal of Arachnology 37:101-102.

Coddington, J.A., I. Agnarsson, J. A. Miller, M. Kuntner and G. Hormiga. 2009. Undersampling bias: the null hypothesis for singleton species in tropical arthropod surveys. Journal of Animal Ecology 78:573–584.

Dimitrov D., Hormiga, G. 2009. Revision and cladistic analysis of the orbweaving spider genus Cyrtognatha Keyserling, 1881 (Araneae, Tetragnathidae). Bulletin of the American Museum of Natural History 317:1-140. PDF available via the AMNH research library (very large file).

Hormiga, G. 2008 . On the spider genus Weintrauboa (Araneae, Pimoidae), with a description of a new species from China and comments on its phylogenetic relationships. ZOOTAXA 1814: 1-20.

Hormiga, G. and L. Tu. 2008. On Putaoa, a new genus of the spider family Pimoidae (Araneae) from southern China, with a cladistic test of its monophyly and phylogenetic placement. ZOOTAXA 1792: 1-21.

Kuntner, M., J. Coddington and G. Hormiga. 2008. Phylogeny of extant nephilid orb-weaving spiders (Araneae, Nephilidae): testing morphological and ethological homologies. Cladistics 24: 147-217.

Benjamin PS., Dimitrov D., Gillespie RG., Hormiga, G. 2008. Family ties: molecular phylogeny of crab spiders (Araneae: Thomisidae). Cladistics 24(5): 708-722. (doi: 10.1111/j.1096-0031.2008.00202.x)

Lopardo, L. and G. Hormiga. 2008. Phylogenetic placement of the Tasmanian spider Acrobleps hygrophilus (Araneae, Anapidae) with comments on the evolution of the capture web in Araneoidea. Cladistics 24: 1-33.

Dimitrov D., Álvarez-Padilla F., Hormiga G. 2008. Until dirt do us apart: on the unremarkable palp morphology of the spider Sternospina concretipalpis Schmidt& Krause, 1993, with comments on the genus Prionolaema Simon, 1894 (Araneae, Tetragnathidae). ZOOTAXA, 1698: 49-56. 

Alvarez-Padilla, F. and G. Hormiga. 2008. A protocol for digesting internal soft tissues and mounting spiders for scanning electron microscopy. Journal of Arachnology 35: 538-542.

Dimitrov D., Alvarez-Padilla F., Hormiga,G. 2007. The female genitalic morphology of the orb weaving spider genus Agriognatha (Araneae, Tetraganthidae). Journal of Morphology 268(9): 758-770.

Hormiga, G., F. Alvarez-Padilla and S.P. Benjamin. 2007. First records of extant Hispaniolan spiders of the families Mysmenidae, Symphytognathidae and Ochyroceratidae (Araneae), including a new species of Ochyrocera. American Museum Novitates 3577: 1-21.

Lopardo, L. and G. Hormiga. 2007. On the spider genus Cepheia Simon 1894(Araneae, Synaphridae). American Museum Novitates 3575: 1-18.

Ramírez, M.J., J.A. Coddington, W.P. Maddison, P.E. Midford, L. Prendini, J. Miller, C.E. Griswold, G. Hormiga, P. Sierwald, N. Scharff, S.P. Benjamin, and W.C. Wheeler. 2007. Linking of Digital Images to Phylogenetic Data Matrices Using a Morphological Ontology. Systematic Biology, 56 (2): 283-294.

Lopardo, L., G. Hormiga and A. Melic. 2007. Spinneret spigot morphology in synaphrid spiders (Araneae, Synaphridae), with comments on the systematics of the family and description of a new species of Synaphris Simon 1894 from Spain. American Museum Novitates, 3556: 1-26.

Hormiga, G. and S. Lew. 2005. Chapter 48: Pimoidae. In: Darrell Ubick, Pierre Paquin, Paula E. Cushing, & Vince Roth (eds.) Spiders of North America: an identification manual (pp. 197-198). Download PDF

Hormiga, G., D.J. Buckle and N. Scharff. 2005. Nanoa, an enigmatic new genus of pimoid spiders from western North America (Pimoidae, Araneae). Zoological Journal of the Linnean Society 145:249-262. Download PDF

Hormiga, G. and N. Scharff. 2005. Monophyly and phylogenetic placement of the spider genus Labulla Simon, 1884 (Araneae, Linyphiidae) and description of the new genus Pecado. Zoological Journal of the Linnean Society 143:359-404. Download PDF

Miller, J.A. and G. Hormiga. 2004. Clade Stability and the Addition of Data - A Case Study from Erigonine Spiders (Araneae: Linyphiidae, Erigoninae). Cladistics 20: 385-442. (cover article) Download PDF Download Software (Pest 3.0)

Hormiga, G. 2003. Weintrauboa, a new genus of pimoid spiders from Japan and adjacent islands, with comments on the monophyly and diagnosis of the family Pimoidae and the genus Pimoa (Araneoidea, Araneae). Zoological Journal of the Linnean Society, 139: 261-281. Download PDF

Hormiga, G., Arnedo, M. Gillespie, R. G. 2003. Speciation on a Conveyor Belt: Sequen-tial Colonization of the Hawaiian Islands by Orsonwelles Spiders (Araneae, Linyphiidae). Systematic Biology 52(1): 70-88 (cover article). Download PDF

Hormiga, G. 2002. Orsonwelles, a new genus of giant linyphiid spiders (Araneae) from the Hawaiian Islands. Invertebrate Systematics 16:369-448 (cover article). Download PDF

Hormiga, G., N. Scharff, and J. Coddington. 2000. The Phylogenetic Basis of Sexual Size Dimorphism in Orb-Weaving Spiders (Araneae, Orbiculariae). Systematic Biology 49(3):435-462. Download PDF

Hormiga, G. 2000a. Higher level phylogenetics of erigonine spiders (Araneae, Linyphiidae, Erigoninae). Smithsonian Contributions to Zoology, 609:1-160.

Griswold, C., J. Coddington, G. Hormiga, and N. Scharff. 1998. Phylogeny of the orb web building spiders (Araneomorphae, Orbiculariae). Zoological Journal of the Linnean Society, 123:1-99. Download PDF

Coddington, J.A., G. Hormiga, and N. Scharff. 1997. Giant Female or Dwarf Male Spiders? Nature, 385:687-688. Download PDF

Hormiga, G., W.G. Eberhard, and J.A. Coddington. 1995. Web construction behavior in Australian Phonognatha and the phylogeny of nephiline and tetragnathid spiders (Araneae, Tetragnathidae). Australian Journal of Zoology, 43:313-364. Download PDF

Hormiga, G. 1994a. A revision and cladistic analysis of the spider family Pimoidae (Araneae: Araneoidea). Smithsonian Contributions to Zoology, 549:1-105.

Hormiga, G. 1994b. Cladistics and the comparative morphology of linyphiid spiders and their relatives (Araneae, Araneoidea, Linyphiidae). Zoological Journal of the Linnean Society, 111:1-71. Download PDF

Hormiga, G. 1993a. Implications of the phylogeny of Pimoidae for the systematics of linyphiid spiders (Araneae, Araneoidea, Linyphiidae). Memoirs of the Queensland Museum, 33(2):533-542.

For reprint requests, please send an email to hormiga@gwu.edu

BiSc 210 - Phylogenetic Systematics (Fall)
BiSc 213 - Principles of Taxonomy: Documenting Diversity (Fall, even years)
BiSc 214 - The Phylogenetic Basis of Comparative Biology (Fall, odd years)
BiSc 207 - Current Topics in Systematic Biology
Courses in Systematics and Evolution at GWU

Daniela Andriamalala (Ph.D. Student. Systematics of goblin spiders, Oonopidae).

Ligia Rosario Benavides (Ph.D. Student. Systematics of pirate spiders, Mimetidae)

Thiago da Silva Moreira (Ph.D. Student. Systematics of Linyphiidae)

Jesus Ballesteros Chavez (Ph.D. Student)

Robert Kallal (Ph.D. Student)

Suresh Benjamin (ATOL: Assembling the Tree of Life: Phylogeny of Spiders)

Dimitar Dimitrov (PEET: Systematics and Monography of Araneoid Spiders)

Jeremy Miller (Ph.D. 2003); Ingi Agnarsson (Ph.D. 2004); Matjaz Kuntner (Ph.D. 2005); Fernando Alvarez-Padilla (Ph.D. 2007); Lara Lopardo (Ph.D. 2009)

	Systematics and Monography of Araneoid Spiders
	LinyGen: Linyphioid Genera of the World (Pimoidae and Linyphiidae), an Illustrated Catalog
	International Society of Arachnology
	American Arachnological Society
	Arachnology Home Page
	Willi Hennig Society
	Systematic Biology
	Zoological Record
	Nomenclator Zoologicus
	NSF-PEET program