Cosmophasis umbratica Simon 1903

Hurni-Cranston, Tiziano & Hill, David E., 2021, Three new jumping spiders of the genus Cosmophasis from Wallacea (Araneae: Salticidae: Chrysillini), Peckhamia 228 (1), pp. 1-84 : 46

9. Cosmophasis umbratica Simon 1903

Figures 41-45 , Map ( Figure 1 ) #57

A series of studies of the courtship and agonistic behavior of Cosmophasis umbratica have been published in recent years, based on spiders collected in Singapore (Lim & Li 2004, 2006a, 2006b, 2007, 2013; Lim, Land & Li 2007; Lim, Li & Li 2008; Taylor & McGraw 2007). Land et al. (2007) described the layered structure of iridescent, ultraviolet reflecting scales of this species, and Bulbert et al (2015) later studied the predatory cost of male ornamentation. With all of these studies, one might assume that this species is well-known. That is not the case. The only descriptions that we have for C. umbratica are Simon's original but brief text description of a male, and subsequent drawings of Simon's male specimen by Prószyński (1984). Both appear here in their entirety, with a new English translation of Simon's description, in Appendix 5. Dyal (1935) listed an all-black 5 mm female with diminuitive ALE from remote Lahore, Pakistan under C. umbratica . That specimen is definitely not a Cosmophasis . Thus the female of C. umbratica , though often subject to study, has never been described.

But even the description of the male ( Simon 1903b; Prószyński 1984) is problematic. There is little here to suggest that C. umbratica is anything other than a synonym for C. thalassina . This is supported by the fact that the type for C. thalassina came from Bintan Island (see Appendix 4), near Singapore where C. umbratica has been most often observed. The drawing of the male pedipalp of C. umbratica by Prószyński (1984) differs somewhat from more recent published ( Żabka & Waldock 2012) images of the pedipalp of C. thalassina in that the rotation of the pedipalp in the former is about 220°, the latter 160°. However this does not account for the possibility of intraspecific variation, or the possibility that Prószyński's drawing is either skewed in angle or inaccurately drawn.

At present the two species cannot be reliably separated in the field. Those identified as C. umbratica have either a locality closer to Singapore than to Australia, males with more gold-colour in their iridescent scales, or females with more colourful scale colour. But we also know that female C. thalassina are quite variable in colouration, even in Australia, with distinct to indistinct transverse bars across the dorsal opisthosoma. In Figures 41-45 we present a series of photographs of males and females that could be identified as C. umbratica , as well as photographs of immatures from the same areas. The immatures are similar to the immature C. thalassina shown above ( Figures 39-40 ).

Figures

Figure 1. Known occurrence of Cosmophasis species in Sunda, Sahul and adjacent oceanic islands. Better-known species are identified in the key at upper right. See Appendix 1 for identification of the other species, most know from a single locality, by number. The new species described here are from Ambon and the Banda Islands within the Wallacean region (small yellow rectangle near the center), shown in more detail in Figure 2. Localities are based on references cited in Appendix 1, as well as reliable photographs posted in iNaturalist and FLICKR. Note that some records of C. thalassina (52, generally found to the south) and C. umbratica (57, generally found to the north) are most likely confused, as separation of these species may not be possible. Background image courtesy of NASA/USGS/Landsat.

Figure 39. Immature Cosmophasis thalassina from Bali. 1-5, Earlier instar. 6-10, Later instar.

Figure 40. Immature male Cosmophasis thalassina from Bali. 1-5, Earlier instar. 6-9, Penultimate.

Figure 41. Adult male Cosmophasis umbratica from Ubud, Bali. Photographs © Norm Farmer (normfarmerimages), used under a CC BY-NC 4.0 license (Farmer 2018a, 2018b, 2018c).

Figure 42. Adult male Cosmophasis umbratica from Singapore. 1-4, Ang Mo Kio Town Garden West. 5-7, Mandai Track. Photographs © Nicky Bay, used with permission.

Figure 43 (continued on next page). Adult female Cosmophasis umbratica from Singapore. 1-4, Pasir Ris Park. Photographs © Nicky Bay, used with permission.

Figure 44. Adult female Cosmophasis umbratica from Singapore. Photographs © Kwan Han (www.NatureLoveYou.sg), used with permission.

Figure 45. Immature Cosmophasis umbratica from Singapore. 1-2, Penultimate male from Sugei Buloh Wetland Reserve. 3-6, Immature or penultimate female. Photographs © Nicky Bay, used with permission.