radiolaria - rads_cat - Collozoum longiforme radiolaria - rads_cat - Collozoum longiforme

CATALOG OF ORIGINAL DESCRIPTIONS: Collozoum longiforme Swanberg & Harbison 1980

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: rads_cat -> C -> Collozoum -> Collozoum longiforme
Other pages this level: C. amoeboides, C. brandti, C. caudatum, C. contortum, C. discoideum, C. ellipsoides, C. fulvum, C. hertwigi, C. longiforme, C. minus, C. moebii, C. nostochinum, C. ovatum, C. radiosum, C. serpentinum, C. stellatum, C. vermiforme, C. volvocinum

Collozoum longiforme

Citation: Collozoum longiforme Swanberg & Harbison 1980
taxonomic rank: species

Current identification/main database link: Collozoum longiforme Swanberg & Harbison 1980


Original Description

Diagnosis. Form of colony cylindrical, 5 to 7 mm diameter with distinct but slightly irregular border, rounded at ends, occasionally branched. Central capsules without shells, roughly spherical, may be elongate in early vegetative stage, diameter of central capsules 50 to 120 gm. Central capsule wall thin but visible, thin proximal ectoplasm. Small oil droplets in early vegetative stage; large oil droplet in late vegetative stage. No spicules present. Gelatin firm. Abundant zooxanthellae; 14 to 50 algae per central capsule.
Description. The vegetative colonies of C. longiforme make it one of the most easily recognizable species of Collozoum. They range from 1 cm to 3 m in length; most are between 30 cm and 1 m ; small colonies (3 to 5 cm) may be shaped like a lobed torus. Each colony (Fig. 2a) has a translucent core composed of small alveoli (approximately 1 mm in diameter), central capsules, and zooxanthdlae. The core makes up about four-fifths of the colony diameter. The core is surrounded by a transparent layer of gelatin (Fig. 2b) in which dense rhizopodia, algae, and captured prey are found. Early vegetative colonies have central capsules 50 to 80 ~ in diameter with small oil droplets (8 ~tm). There are from 14 to 28 algae per central capsule (Table 2). Late vegetative colonies have central capsules 80 to 120 ~tm in diameter with a single large oil droplet (35 to 55 ~tm). In the latter colonies, there are up to 50 algae per central capsule. The solitary and reproductive stages are unknown. The gelatin is firm; a diver can gently grasp a 1 m long colony in the middle region and drag it along while swimming slowly. The colony keeps its shape in a small dish and does not break when dangled from a smooth rod. We know of no other cylindrical radiolarian colony which is this durable. The gelatin is poorly fixed with chromic acid or with I2-ethanol. In formalin, the colony disintegrates after several days. In picric acid- formalin, the colony form is preserved indefinitely.
Type locality. Equatorial epipelagic region east of the north coast of Brazil to St. Peter and Paul Rocks (Holotype and Paratypes Sta. 773; 6°08'S, 31°46'W).
Holotype. A holotype specimen will be deposited with the U.S. National Museum. Station Numbers: 542-549,551,557-560, 562-564, 566, 567,571-573,760, 762, 764-773.
Comments. From studies of living radiolarians, we have found the following characters to be of taxonomic importance: (1) colony shape (spherical, cylindrical), (2) colony diameter (1 to 2 mm, 2 to 5 mm, 5 to 7 mm), (3) central capsule shape (spherical, serpentine, polygonal, ameboid) and size (< 50 ~tm,50 to 150 ~tm, > 150 ~tm),and (4) appearance of the central capsule wall (delicate, thin, or thick, stout). These characters have been used by previous researchers to distinguish Collozoum species (BRANDT,1885;HAECKEL,1862, 1887). All but character (2) can usually be observed in carefully preserved material. There are a number of other useful characters that may vary with developmental stage or are more subjective: (1) size and arrangement of alveoli (segmentation in cylindrical colonies), (2) number of layers of nuclei (single or double), (3) thickness of proximal ectoplasm ("Pseudopodienmutterboden", BRANDT,1885) and presence or absence of "Assimilations- plasma" (osmiophilic substance in proximal ectoplasm), (4) thickness and abundance of pseudopodia, (5) consistency of gelatin; its reaction to fixatives (dissolves in formalin, fixed in Cr20~-2 and I2-ethanol, etc.), its firmness and transparency (firm, soft; visible, invisible) and the sharpness of the colony border (distinct or fuzzy with rhizopodia), (6) the number of algae per central capsule (< 10, 10 to 100, > 100), and (7) the number and distribution of oil droplets (1, a few, many). All but character (5) can be observed in carefully-preserved material. There are several other characters we consider useless: (1) algal cell distribution (on central capsules or in gelatin matrix), (2) presence or absence of oil droplets, (3) the development of anisospores (shown to be parasites by HOLLANDE and ENJUMET, 1953), (4) color of oil droplets, and (5) presence or absence of spicules. Using descriptions in the literature and the "good" characters, C. longiforme can be separated from all previously-described species (Table 2). Collozoum fulvum, C. hertwigi, C. serpentinum, C. vermiforme and C. ameboides all form spherical colonies. Collozoum coeruleum, C. inerme, C. radiosum, C. moebii, and C. minus all have smaller diameters than C. longiforme. Collozoum nostochinum, C. volvocinum, C. ovatum, and C. ellipsoides all have larger central capsules. Collozoum pelagicum, C. discoideum, and C. stellatum have polygonal or assymetrical central capsules. BRANDT(1885) described eight additional forms of Collozoum, none of which he named, and none of which resembles C. longiforme. Neither do the forms described from preserved material by HASWELL and HEDLEY (1907). The longest colony of Collozoum hitherto reported was that of C. moebii (BRANDT, 1905), which reaches a length of 40 cm. The vegetative stage of Collozoum (= Myxosphaera) coeruleum as figured by BRANDT (Taf. I, Fig. 40, 1885) resembles C. longiforme, but the diameter of the colony is 2.5 mm. The central capsules are regular spheres. The largest are slightly smaller than early vegetative C. longiforme (45 to 67 ~tm), the algae : central capsule ratio is lower (1 to 4 : 1) and the membrane is thick and heavy.

References:

Swanberg, N. R. & Harbison, G. R. (1980). The ecology of Collozoum longiforme, sp. nov., a new colonial radiolarian from the equatorial Atlantic Ocean. Deep-Sea Research. 27(9A): 715-731. gs


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Collozoum longiforme compiled by the radiolaria@mikrotax project team viewed: 21-7-2024

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