Chiropsalmus zygonema Haeckel, 1880

Gershwin, Lisa-Ann, 2006, Comments on Chiropsalmus (Cnidaria: Cubozoa: Chirodropida): a preliminary revision of the Chiropsalmidae, with descriptions of two new genera and two new species, Zootaxa 1231 (1), pp. 1-42 : 11-12

Chiropsalmus zygonema Haeckel, 1880

No figure ever published

Chiropsalmus zygonema Haeckel, 1880: 641 , n. sp. — Mayer, 1910: 517. — Thiel, 1928: 15–16; = juvenile C. quadrigatus . — Southcott, 1956: 277; probably immature. — Kramp, 1961: 310. — Gershwin, 2005: 124­125 and throughout; taxonomy and phylogeny.

Type locality South Atlantic Ocean , off the coast of Argentina .

Material examined No types or other material known.

Diagnosis

Body to about 60mm BH, 40mm BD; with two asymmetrical tentacles on each pedalium; finger­like gastric saccules rudimentary.

Description (electronically translated from Haeckel, 1880, with as much of the original terminology as possible in order to minimize erroneous interpretation)

Species­Diagnose: Umbrella four­sided­pyramidal, vaulted above, with inclusion of the hanging velarium 1 1/2 times as high as wide. Mouth­tube small, four­lipped, half so long as the roundish stomach­sack whose 4 interradial side­walls carry arched phacellae. The two gastric saccules about the umbral­wall of each radial­pocket, close to the entrance, oval, very small. Four pedalia page­form, two­edged, asymmetrically arranged, approximately 1/3 as long as the umbrella­height, each with 2 short jelly fingers. In total 8 long tentacles.

Specielle description: Chiropsalmus zygonema is interesting as the simplest under the Chirodropidae until now examined, which directly joins this Subfamily with the Tamoyidae . In total, this type resembles more of a Tamoya than a Chiropsalmus , but must be put more to the last genus however, since each pedalium carries 2 tentacles. Indeed this condition also occurs as individual variation with the 4­tentacled Tamoya haplonema however (P. 443). Velarium and gonads is similarly like with C. quadrumanus (P. 447).

Size: Umbrella­width 40 mm., umbrella­height 60 mm.

Place of discovery: South Atlantic Ocean, at the Argentinian coast, Smith.

Remarks

Thiel (1928) came to a most curious conclusion about this species, believing it to be an immature Chiropsalmus quadrigatus , even though C. zygonema with apparently immature characters is larger than the comparable specimen of C. quadrigatus . One might logically expect a progressive pattern of development among conspecifics. Thiel also noted that the two species are widely separated geographically, but dismissed it by stating that many cubozoans have wide distributions. In fact, many of the previously assumed widespread species are proving to be comprised of numerous distinct species, and at least in Australia, chirodropid and chiropsalmid species have very tight distributions.

Based on distribution, C. quadrumanus would have been a better assumption, because at least C. quadrumanus and C. zygonema are known from the same ocean (Atlantic). However, an ideal method of identification would have been based on structural characters, and C. zygonema with blade­like pedalia would not have been attributable to any other species. Furthermore, with two fingers and tentacles, it would not have seemed similar to other species, which typically have 4–6 at a similar size (e.g., Chiropsella bronzie gen. et sp. nov. (see below) and Chironex fleckeri , unpublished notes).

I am provisionally keeping C. zygonema in the restricted genus Chiropsalmus because I suspect that C. alipes n. sp. (described below) may hold the key to its identity. This peculiar form from the Pacific coast of southern Mexico is small at maturity, has exumbrellar warts like C. quadrumanus , and has very peculiar carybdeid­like pedalia, such as those described for C. zygonema . Whether the Mexican form and C. zygonema are identical will probably never be known, because there is no known type material of C. zygonema , and Haeckel left no drawings and only a very brief description. I think the most stable course of action is to regard this species as provisionally valid, but to recognize that it is currently represented by an unrecognizable juvenile form, and thus needs to be redescribed based on an adult form from near the type locality.