Chiropsoides quadrigatus ( Haeckel, 1880 ) Gershwin, 2006

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 : 22-24

Chiropsoides quadrigatus ( Haeckel, 1880) , comb. nov.

Plate 3E, F

Chiropsalmus quadrigatus Haeckel, 1880: 447 . — Mayer, 1910: 516–517 [in part]. — Stiasny, 1922: 517; examination of holotype. — Thiel, 1928: 13–14, fig. 6; examination of type specimen. — Stiasny, 1937: 213–217 [in part]; comparison with specimen from the Maldive Archipelago. — Kramp, 1955: 162; examination of holotype. — Kramp, 1961: 309 [in part]. — Mianzan & Cornelius, 1999: 533 [in part]; may be conspecific with Chiropsalmus quadrumanus .

Chiropsoides quadrigatus — Gershwin, 2005: 126–127, pl. 4.10C, D and throughout; taxonomy and phylogeny.

non Chiropsalmus quadrigatus . — Mayer, 1910: 516–517, fig. 331. — Mayer, 1915: 171–172 [= one or two undescribed species (see below)].

non Chiropsalmus quadrigatus . — Stiasny, 1937: 213–217, figs. 4–9; redescription from Maldives [= unidentified, compare with Chironex sp. ].

non Chiropsalmus quadrigatus . — Barnes, 1965: 13–22, figs. 4, 6, 8, 10, 11d–f, 13, 15; Australian form, comparison with Chironex [= Chiropsella bronzie gen. et sp. nov. (see below)].

Many other references exist to the name Chiropsalmus quadrigatus , but apparently do not refer to medusae conspecific with Haeckel’s type specimen. Because the name C. quadrigatus has long been associated with characters distinctly different from those of the type, those medusae identified with the name were very likely characterized by non­ C. quadrigatus morphology. While it is impossible at this point to determine the proper identification of each, certain generalizations can be made based upon the species that actually are found at these problematical locations, especially those whose morphology resembles that which was mistakenly thought to represent C. quadrigatus . However, such generalizations must be made with great caution, as it is entirely possible that additional closely related forms will be discovered throughout the Indo­Pacific, thus revisiting the same problem. It must be emphasized that species identification must be based on evaluation of many morphological characters, not on geographic occurrence or on possession of a single character.

At the present time, all Chirodropida from Australia, the Philippines, Japan, and throughout southeast Asia should be assumed to belong to species other than C. quadrigatus . Within Australia alone, there are at least four new species of Chirodropida that are in the process of publication; more can be expected to be found. Similarly, it follows that a diversity of species will be found throughout the tropical Indo­Pacific.

Material examined

Holotype: ZMUC unnumbered (= Haeckel #166), Indian Ocean , 10 miles off Rangoon, Burma, coll. by Thallitzer, 18 Nov 1863; 51.86mm BH, 61.44mm crumpled DBW, 29.50mm IRW, 2.14mm TBW.

Type locality Indian Ocean, 10 miles off Rangoon.

Diagnosis Cannot be accurately diagnosed at this time based on immaturity of the holotype.

Revised description

Specimen is immature and in extremely poor condition ( Plate 3E ). Exumbrella apparently lacking nematocysts and circum­aboral furrow; with prominent interradial pillars, divided by shallow interradial furrow, set off from flat sides of body by deep vertical adradial furrows. Pedalia with 3 or 4 fingers and tentacles, unilaterally arranged. Pedalial canal flat throughout length; with upward­pointing thorn at bend; with a raised ‘bump’ on proximal end of the longest canal ( Plate 3F ). Tentacles flat, ribbon­like, flared slightly at the base. Rhopalial niche raised, dome­shaped; ostium flat on bottom, W­shaped on top. Gastric saccules either missing or not yet developed, but a small, solid gelatinous knob is present in the perradii. Gonads apparently not yet developed.

Distribution No additional specimens identifiable with this species are presently known.

Remarks

This species has been problematical since the brief and insufficient description given by Haeckel (1880) as Chiropsalmus quadrigatus . Based on a single immature and badly damaged specimen from Rangoon, and lacking illustrations, previous workers were unable to determine the exact nature of the species and thus it has become a catch­all for most Indo–Pacific Chirodropida . Mayer (1910; 1915) redescribed the species based on Philippine material, but this was apparently based on two different species (Gershwin, unpublished notes). Stiasny (1922) and Kramp (1955) both commented that they were unable to determine the proper identity of the holotype. This uncertainty has led to many different forms from widely disparate locations around the Indo–Pacific being assigned to the species, including a North eastern Australian form (described below as Chiropsella bronzie gen. et sp. nov.), two Philippine forms (awaiting description), and at least one Japanese form (awaiting description). At least some of these are apparently lethal to humans.

Mianzan & Cornelius (1999) speculated that C. quadrigatus may be conspecific with C. quadrumanus ; this is untenable for several reasons. First, of the few characters that can be interpreted from the C. quadrigatus holotype, the only shared characters with C. quadrumanus are very general, such as a cuboid body shape and the fact that the pedalia are branched, but the two forms differ in numerous major structural characters such as the pattern of the pedalial branching, pedalial canal form, pedalial bend morphology, presence of exumbrellar nematocysts, and tentacle shape. Second, there is no a priori reason to presume that a western Atlantic species would be the same as an Indian Ocean species, lacking geographic intermediates. Even forgiving the reliance on previous inaccurate identifications of C. quadrigatus from Australia and the Philippines, this still would be insufficient reason to assume conspecificity of the two forms. Third, no interpretable description of C. quadrigatus exists in the literature, and there is no evidence that either Mianzan or Cornelius have examined the holotype to be able to make an evidence­based assessment.

I have examined the holotype and have concluded that it is most closely similar to the later­described Indonesian species Chiropsoides buitendijki ( Horst 1907) , not to the Philippine forms. In C. quadrigatus , the pedalia fork in a conspicuous unilateral manner; this is not known in any other species except C. buitendijki . Both species possess a similar upward­pointing ‘spike’ near the base of the pedalial canal, which differs from the Philippine species. And like C. buitendijki , C. quadrigatus has flat, ribbon­like tentacles; in the Philippine species they are more rounded. Most other useful characters of the C. quadrigatus holotype are indeterminable. However, in C. buitendijki the main canal has a series of knobs between the forks, whereas in the C. quadrigatus holotype the main canal has knobs on the forks themselves but not between. I would not normally consider the location of the knobs to be of specific difference, but I think it would be foolhardy at this point to consider the two forms conspecific without further evidence. Based on my experience with other cubozoans, it seems likely that the Burmese and Javanese forms are distinct, given their geographic separation. As such, the Indian records of C. buitendijki are more likely to be referable to C. quadrigatus , but such a determination should be made on their morphology, not on geography. On the other hand, if the two forms are found to be identical, then the name C. quadrigatus would have priority. While it is possible that future studies will demonstrate that they are conspecific, until the ontogenetic changes of both forms can be studied, the two should be maintained as separate species in order to maximize stability.

Figures

PLATE 3. Chiropsoides spp. A. Chiropsoides buitendijki, syntype specimen, preserved. B. C. buitendijki, pedalium. C. C. buitendijki, gastric saccules (arrow). D. C. buitendijki, Sri Lanka, velarial canals. E. C. quadrigatus, holotype, preserved. F. C. quadrigatus, pedalium; note bulge on canal (arrow).