20th International Congress of Arachnology

DENVER MUSEUM OF NATURE & SCIENCE

REPORTS

No. 3, July 2, 2016

International Congress of Arachnology

Due to the relative highest diversity of the family Styg-

nopsidae (Grassatores: Gonyleptoidea), its unknown

relationships and the increasing taxonomic works in the

last years, we performed a phylogenetic analysis concern-

ing this family. We produced four datasets: three molecular

markers, partial ribosomal 28S, mitochondrial ribosomal

16S, mitochondrial protein-encoding Cytochrome c

oxidase subunit I (COI), and 72 morphological characters.

With these data, we performed three different phylogenetic

analyses: Bayesian Inference with molecular data, and

Bayesian and Maximum Likelihood using combined data.

In our results we recovered the monophyly of Stygnopsi-

dae, with two major clades within the family, considered

and diagnosed as two subfamilies: Stygnopsinae and a new

subfamily assignment. According to the results and due

to the polyphyly of

Hoplobunus

and

Paramitraceras

, the

following genera were redefined:

Stygnopsis

Hoplobunus

and

Serrobunus

stat. rev., also we detected a new genus

to allocate

Hoplobunus spinooculorum

. Additonally, the

following taxonomic changes are proposed:

Serrobunus

queretarius, Stygnopsis apoalensis, Stygnopsis mexicana

and

Stygnopsis oaxacensis

new combinations. Finally, we

discuss the evolution of male genitalia and the importance

of some homoplastic characters.

Keywords: Laniatores, taxonomy, new subfamily, homo-

plastic, male genitalia

Oral presentation

Late Ordovician chelicerate diversity - new

insights from Manitoba Konservat-Lagerstätten

Michael B. Cuggy

, David M. Rudkin

, Graham A. Young

Department of Geological Sciences, University of

Saskatchewan, Saskatoon, SK S7N 5E2, Canada;

Department of Natural History (Paleobiology), Royal

Ontario Museum, 100 Queen’s Park, Toronto, ON M5S

2C6, Canada;

The Manitoba Museum, 190 Rupert

Avenue, Winnipeg, MB R3B 0N2, Canada

Michael.cuggy@usask.ca

Two recently discovered Konservat-Lagerstätte deposits in

central and northern Manitoba are yielding many exciting

new fossils. Some of these provide a compelling (and often

confounding) record of emerging chelicerate arthropod

diversity in Late Ordovician (Richmondian) restricted

shallow marine environments of central Laurentia.

Biotic assemblages from the William Lake (Grand Rapids

Uplands; Williston Basin) and Airport Cove (Churchill area;

Hudson Bay Basin) sites both contain representatives of

the early xiphosurid horseshoe crab

Lunataspis aurora

including juvenile individuals revealing allometric growth

of the prosomal shield and telson. Elements of unusual new

eurypterid taxa have so far been identified from William

Lake. It possesses a puzzling chimera-like combination

of exoskeletal characters, including a novel swimming

paddle morphology, setting it apart from all other described

forms. The William Lake section, in addition, includes the

first Ordovician record of a sea spider - the only known

fossil occurrence of the rare and bizarre Pycnogonida in

rocks of demonstrable shallow-water origin. Fragmentary

remains of other non-biomineralizing arthropods found

at both sites hint that other chelicerate groups, such as the

‘synziphosurines’ and chasmataspidids, may be present.

These discoveries provide a unique window into the early

radiation of the chelicerate arthropods and suggest that

Ordovician marginal marine habitats may have been the

setting for much of their initial diversification.

Keywords: fossils, marine, evolution

Oral presentation

Dual function of male genitalia in

Tetrag-

natha

–sperm removal and sperm transfer

Anne Danielson-Francois, Yevhen Drobot

University of Michigan - Dearborn, Department of

Natural Sciences, 4901 Evergreen Road, Dearborn,

MI 48128, USA

danfranc@umich.edu

Male long jawed orb weavers of the genus

Tetragnatha

have several unusual pedipalp structures. The most strik-

ing is the elegant corkscrew-like spiral of the conductor,

which guides the sperm releasing embolus to its final

destination. We have demonstrated that this structure,

in concert with other features, removes stored rival male

sperm and biases paternity towards the last male in the

species

Tetragnatha elongata

(Walckenaer, 1841). In

addition to removing stored rival sperm, male

T. elongata