Note that the California Academy of Sciences Types Database page for this specimen is here...and large-size images (e.g. 2679 x 2007) are accessible from that page.

Van Duzee's 1914 protologue (see here), indicated his species description was based on a number of specimens (i.e. syntypes) whose sexes were not indicated...and none was chosen as a holotype. The aforementioned specimen page indicates the individual seen here was chosen as a lectotype, but it doesn't indicate its sex. When all other things are equal, I think the convention is to choose a male specimen for a lectotype...but I don't think it's obligatory. However, the CAS Types Database has a companion specimen page for the allotype of S. nigricans...and that page explicitly indicates the allotype is a female. Presumably the allotype was chosen in association with this lectotype, and thus the post here should be a male.

[PS: If you know how determine the sex here from the photos (I don't!), and believe this is a female...please correct me!]