Jassa algensis ( Nardo, 1847a )

Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, Zootaxa 4939 (1), pp. 1-191 : 159

Jassa algensis ( Nardo, 1847a)

Originally named Cancer algensis by Stefano Chiereghin in an unpublished manuscript, this species, from the Venice lagoon, was mentioned in two publications by Nardo in 1847. Nardo (1847a, p. 132) described “... Cancer algensis, Chiereghin , sp.60, fig. 76–79, which has the peculiarity of weaving a garment shaped like a cornucopia on the leaves of the zostera within which it is hidden like the larvae of the Friganee. This was believed by Leach a Podocerus , but should be regarded as a new genus that we named Lusyta , next to Atylus, Leach , and Carapus, Say. ” (translated from Italian). Nardo (1847b) gave a short Latin description of Lusyta algensis which is of no help in deciphering whether this species is in the genus Jassa . Nardo (1869) illustrated Lusyta algensis , showing two figures of its tubes which appeared to be attached to a substrate (one figure life-sized and one enlarged), and two figures of the full body (one figure life-sized and one enlarged). The illustrations are small, but some features are evident.

Tubes: the two tubes shown are conical, not cylindrical, and curved. The tubes appear to be open only at one end, with the open head end being 2.5x the width of the closed tail end. The two tubes overlap each other at about 90° with the head of each tube farthest from the other head. The length of the tube in the life-sized illustration is about 7 mm.

Body length: the length of the full body in the life-sized illustration is about 6 mm.

Antennae 1 and 2: are both slender and about the same length.

Gnathopods: the illustration of the full body (enlarged) shows the two gnathopods to be no larger than the pereopods.

Illustration of other features, such as the morphology of the third uropod were too small to assist with determining taxonomic status. Nardo’s description of Lusyta algensis sheds further light by stating that “The first two feet are large, equal...” ( I primi due piedi sono grossetti, eguali…).

Stebbing (1906) listed Lusyta Nardo, 1847a and L. algensis Nardo, 1847a under the title “Gammarideorum genera dubia et species dubiae.” Two features of the illustrations and description in Nardo (1869) suggest that Lusyta algensis is not Jassa : the equally sized gnathopods, and the appearance of the tube. In Jassa , the second gnathopod is so enlarged compared to the first (even in the female and juvenile) that this should be evident both in the description and in the drawings made by Nardo (1869). The tubes are not Jassa -like. Jassa builds a cylindrical tube which is open at both ends, not a curved, conical tube that is open only at one end. Therefore, it is unlikely that Nardo’s Lusyta algensis is in fact Jassa at all. To confirm this is not possible, unfortunately, as most of the Nardo collection has been lost and what is left has no labels (pers. comm. with Roberta Salmaso, Museo Civico di Storia Naturale, Verona, 17 July 2018).