Chiropsalmus alipes, 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 : 12-16

Chiropsalmus alipes , sp. nov.

Plate 2

Material examined

Holotype: SIO PIC­060222­0001 ­HT, 6 April 1971, Zihuatenejo , Mexico, 17°08’N, 101°02’W, coll. Scripps Inst. Oceanogr. MV 73 ­I­29; male, 115.0mm BH, 99.5mm DBW, 56.0mm IRW, 4.00mm TBW, 60.0mm pedalial length total (51.0mm to end of adaxial keel), 5.5mm pedalial canal width, 7.5mm abaxial keel width, 10.0mm adaxial keel width.

Paratypes: SIO PIC­060222­0002 ­PT, same data as holotype; male, 91.0mm BH, 79.5mm DBW (crumpled), 46.0mm IRW, 2.5mm TBW . SIO PIC­060222­0003 ­PT, same data as holotype; 92.0mm BH, 79.5mm DBW, 37.0mm IRW, 2.0mm TBW .

Etymology

From the Latin ‘ala’ (meaning ‘wing’) and ‘pes’ (meaning ‘foot’), in reference to the wing­like pedalia that characterize this species; gender neutral.

Diagnosis

Chiropsalmus with long oar­like pedalia, with ‘fingers’ and tentacles clustered terminally; with short, small, hollow, simple gastric saccules; with warty apical surface, and nematocyst freckles densely scattered on the upper half of the body and in a line on the outer pedalial keel.

Description

Bell shape unknown in life, but somewhat taller than wide, with a rigidly flat­topped apical region ( Plate 2A ). Apical mesoglea not thickened, lacking any trace of circumaboral groove, densely studded with conspicuous gelatinous nematocyst warts. Very small flush nematocyst freckles are scattered on the interradii of the upper 1/3 of the body, and in a single row along the lower half of the outer pedalial keel; nematocyst freckles or warts could not be found on other parts of the body wall or velarium. Mesoglea is thick, probably rigid in life and able to hold its shape out of water; after being in preservative for over 30 years, the mesoglea has lost all stiffness. Interradial pillars thickened and broad, with a well defined interradial furrow running between. Adradial furrows not observed.

Pedalia 4, interradial, very long and spatula­shaped, greatly resembling the pedalia of the Carybdeida, but with short ‘fingers’ and tentacles clustered at the extreme distal end ( Plate 2B ). Fingers and tentacles 3 or 4 per pedalium, arranged in a most peculiar manner ( Plate 2C ): pedalia with 3 tentacles have the one outer tentacle branching in the abaxial direction, plus two opposing tentacles immediately distal to it and perpendicular to that axis and opposite in arrangement to each other; in pedalia with 4 tentacles, at the point where the opposite branches meet, the 4 th (reduced) tentacle originates but branches off in the adaxial plane. The pedalial canal is simple throughout its length, to the point of the terminal 3­way branch. Pedalial canal substantially flattened throughout length; with a conspicuous upward­pointing ‘volcano’ shaped diverticulum near the base. Outer pedalial wings about 1.5x canal width; inner pedalial wings about 2x pedalial canal width. Tentacles thick, round to slightly flattened in cross section, about 2mm wide at base; evenly banded with very small bands, with segmented appearance every 1–2mm. Pedalial canal straight at tentacle insertion. Tentacle base narrower at insertion, flaring a bit distally, like a horse’s hoof.

Rhopaliar niche contour raised conspicuously off body wall. Rhopaliar niche deeply incised, reminiscent of the deep niches of the Tamoyidae . Rhopaliar niche ostia very shallow frown­shaped, with broad, shallowly convex opposing upper and lower covering scales. Rhopaliar horns and rhopaliar stem warts lacking. Two main lensed eyes with dark pigment could be discerned, but the number and arrangement of lateral eyes could not be determined in these preserved specimens. Rhopalial windows flat, overgrown by frenulum.

Velarium broad; with many broad, numerous complexly branched canals with jagged edges ( Plate 2D ), bearing many lateral diverticulations, not anastomosed. Velarial canal roots 1 per octant leaving stomach; with about 5 velarial canals at the point of the velarial turnover; with 10 or more reaching velarial margin. Perradial lappets present but not conspicuously thickened, appearing as one of the velarial canals, narrow, branching into numerous velarial canals along sides; with lateral and distal diverticulations. Velarial nematocyst warts not observed. Frenulum a single, simple sheet, barely extending onto velarium.

Gastric phacellae very bushy, forming a continuous ring of cirri around the edge of the stomach, not in distinct 90º series; microscopically, the cirri are singly rooted in rows. Gastric saccules very small, short, hollow, simple finger­like processes. Perradial mesenteries lacking. Subumbrellar rhopaliar windows flat. Gonads leaf­like, only evident in the holotype to about half the bell height. Stomach shallow and flat. Manubrium about half the length of the subumbrellar cavity. Lips huge, long, broad, straight­edged.

Nematocysts

Tentacle and bell squashes made from the type series did not yield any nematocysts for study.

Variation

Several characters were noted as different from my observations by Dr. R. Hartwick (formerly of James Cook University, Australia) in his unpublished notes. First, whereas I was unable to discern the presence or number of lateral eye spots, Hartwick noted that there were six eyes. All Chirodropida known to date, for which the eyes have been studied, have the full complement of two median lensed eyes and four lateral eye spots; thus, it seems probable that this is accurate and that they have simply faded with time in preservative. Second, perhaps most curiously, Hartwick noted that the gastric saccules were ‘3­scalloped’, and about as long as the manubrium and mouth; in contrast, I was unable to discern any such scalloping, the saccules appeared to me as smooth, and also appeared about half the length of the manubrium and mouth. Finally, Hartwick noted the presence of nematocyst warts on the velarium, whereas I was unable to observe these.

Remarks

Chiropsalmus alipes is immediately identifiable from all other known chiropsalmids in its exaggeratedly long pedalia, greatly resembling the oar­like pedalia of the Carybdeida rather than the claw­like pedalia typical of the Chirodropida . Haeckel (1880) described “blattförmig, zweischneidig” (i.e., page­form, two­edged) pedalia for C. zygonema , with only two asymmetrical fingers and tentacles; however, with no illustrations, no type specimens, and no additional material ever being found, it is difficult to conclude any precise relationship between C. alipes and C. zygonema . Chiropsalmus alipes is further distinguished from most other chiropsalmids by having conspicuous gelatinous warts on the apex of the bell; no mention of bell warts was made for C. zygonema . Chiropsalmus quadrumanus is the only other known chiropsalmid with exumbrellar warts, but they tend to be less pronounced to the touch, and more evenly scattered over the entire bell surface.

Its placement in the genus Chiropsalmus is based on overall morphological similarity; like the type species, C. quadrumanus , this is the only other species described to date with small, simple, pendant saccules, and exumbrellar nematocysts (Table 1). However, the pedalia of C. quadrumanus are more like the typical Chirodropida hand­like or claw­like form, whereas the pedalia of C. alipes are more similar to those of the Carybdeida. Haeckel (1880) interpreted the blade­like pedalia of C. zygonema as a link between the Chirodropidae and Tamoyidae ; however, the remaining characters firmly place C. alipes (and presumably C. zygonema ) in the Chirodropida .

It seems probable that C. alipes is closely related to the enigmatic C. zygonema ; it is also possible that C. alipes is the adult form of C. zygonema . If a specimen had only two tentacles, as in C. zygonema , these might logically be the outer unpaired tentacle and one of the typically paired lower tentacles, thus being asymmetrical. However, it is hard to imagine that the two opposing ‘middle tentacles’ would not have formed together, resulting in three tentacles rather than two, as in C. alipes . Thus, it might be that C. alipes and C. zygonema are closely related but not identical. Furthermore, given the geographical separation of C. alipes off the Mexican Pacific coast and C. zygonema of the Argentine coast, it is doubtful that the two would be identical.

Figures

PLATE 2. Chiropsalmus alipes, n. sp. A. Holotype, preserved. B. Pedalium whole; note prominent keels reminiscent of the Carybdeida (white arrows); note also volcano­shaped bend (black arrow). C. Pedalial branching; note branching in four directions. D. Velarial canals; note broad canals and jagged edges.