Species accounts

French girdle wearer

Nanaloricus mysticus

ORDER Nanaloricida

FAMILY Nanaloricidae

TAXONOMY

Nanaloricus mysticus Kristensen, 1983, off the coast of Roscoff, France.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

The adults measure 0.00894-0.00925 in (227-235 pm). The mouth cone has eight oral ridges. The introvert has eight rows of true scalids; however, the first row of tricoscalid plates is fused with a row of scalids, giving the impression of a ninth row. Both sexes have eight clavoscalids. The male's clavoscalids are all branched except for the midventral pair, which resembles the female's clavoscalids. The last two rows on the introvert are beak- or tooth-like scalids. The lorica consists of six plates with a fine honeycomb structure. Flosculi are present in two pairs on the plates along the back and sides, and as a single flosculum on the anal plate.

The Higgins larvae measure 0.0047-0.0072 in (120-185 pm). The mouth cone lacks an armature (protective structure). The introvert has seven rows of scalids. The accordion-like thorax consists of 5-6 folds. Three ventral pairs of setae are located between the thorax and the abdomen. The lorica has coarse honeycomb ornamentation. Three pairs of anterior setae are modified to form a locomotory organ with grasping function. Three pairs of posterior setae are located on the lorica together with a pair of toes. The toes are flattened by a leaf-like structure called the mucro.

DISTRIBUTION

Roscoff, France. Two previously published records from Florida and the Azores Islands respectively turned out to refer to two undescribed species.

HABITAT

Found in the upper surface layer of Dentalium-sand (a specific type of coarse sand with high concentrations of detritus) at a depth of 65.6-82 ft (20-25 m).

BEHAVIOR

The Higgins larva may be able to swim by using its large leaflike toes as a propeller.

FEEDING ECOLOGY AND DIET

In the first description of the Loricifera, it was postulated that this species is ectoparasitic because one specimen was attached

Pliciloricus Habitat

to a copepod. This finding, however, turned out to be an artifact, or misleading result arising from the way the specimen was prepared. Nanaloricids feed exclusively on bacteria.

REPRODUCTIVE BIOLOGY Sexual reproduction.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Japanese deep-sea girdle wearer

Pliciloricus hadalis

ORDER

Nanaloricida

FAMILY Pliciloricidae

TAXONOMY

Pliciloricus hadalis Kristensen & Shirayama, 1988, Izu-Ogasawara Trench, Western Pacific.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Adults measure 0.0058-0.0086 in (149-219 pm). The males are smaller than the females. Mouth cone is small and without mouth tube. The leg-shaped scalids in the second row are very large and robust. Two of the scalids in the second row are modified into a short and thick double organ. The fourth row has 15 claw-shaped scalids and 15 simple spinoscalids. The tri-choscalids (eight single and seven double) are very long, about 0.0039 in (100 pm). The abdomen consists of 20 plicae. A single pair of Pliciloricus-flosculi is located caudally. Higgins larvae are long and slender, measuring 0.0103 in (262 pm). There are seven rows of scalids. The spinoscalids are long, over 0.00197 in (50 pm). Two pairs of setae are situated between the thorax and the abdomen. The toes are very long, about 0.006 in (153 pm), straight and pointed. Three pairs of setae are located toward the rear of the abdomen.

DISTRIBUTION

The hadal bathymetric zone of the deep sea (below 20,000 ft; 6,100 m). Found in the Izu-Ogasawara Trench off Japan at a depth of 27,100 ft (8,260 m).

HABITAT

Red deep-sea clay.

BEHAVIOR

One specimen was found 1.57 in (4 cm) deep in the clay, which indicates that the animal is capable of burrowing or living in association with a tube-dwelling macrofauna animal.

FEEDING ECOLOGY AND DIET

Probably bacteria.

REPRODUCTIVE BIOLOGY

The mode of reproduction of this species is not understood. The lack of seminal receptacles in the female suggests that this species has external fertilization.

Hadal Zone Animals

CONSERVATION STATUS SIGNIFICANCE TO HUMANS

SIGNIFICANCE TO HUMANS None known. ♦

Bucket-tailed loriciferan

Rugiloricus cauliculus

ORDER Nanaloricida

FAMILY Pliciloricidae

TAXONOMY

Rugiloricus cauliculus Higgins & Kristensen, 1986, off the coast of South Carolina, United States.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Adults measure 0.0071-0.0103 in (180-264 pm). Mouth cone is very small. Introvert with nine rows of scalids. Appearance of the clavoscalids displays sexual dimorphism. Two types of clavoscalids (four large dorsal and four small ventral) are present in the male, but not in the female. The fourth row has 15 claw-shaped scalids and 15 simple spinoscalids. Lorica has 60 plicae. Anal cone pointed. The larvae measure 0.0108 in (275 pm), but are insufficiently described.

DISTRIBUTION

Found on the continental shelf off North and South Carolina, USA; in the Mediterranean Sea; and near the Faroe Islands. The identity of the Faroe Islands specimens is slightly uncertain, however; they may represent a new species.

HABITAT

Coarse phosphorite or oolytic sand at a depth of 656-1,640 ft (200-500 m).

BEHAVIOR

Nothing is known.

FEEDING ECOLOGY AND DIET

Probably feeds exclusively on methano-bacteria.

REPRODUCTIVE BIOLOGY

Sexual and asexual life cycles, including parthenogenesis with neotenous larvae (see Reproductive behavior in main chapter).

CONSERVATION STATUS

Not listed by the IUCN.

American diamond girdle wearer

Rugiloricus carolinensis

ORDER

Nanaloricida

FAMILY

Pliciloricidae

TAXONOMY

Rugiloricus carolinensis Higgins & Kristensen, 1986, South Carolina, United States.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Adults measure 0.008 in (205 pm). Introvert has nine rows of scalids. The clavoscalids in the first row are all uniform. The second row has between 9-15 leg-shaped spinoscalids. The fourth row has 30 uniform spinoscalids. The neck region consists of 15 single trichoscalids. The lorica consists of 30 plicae with a pair of Pliciloricus-flosculi and a large anal field.

DISTRIBUTION

Found on the continental shelf off North and South Carolina, USA, and near the Faroe Islands in the North Atlantic. The specimens from the Faroe Islands may be a new species.

HABITAT

Coarse phosphorite and carbonate sand.

BEHAVIOR

The Higgins larvae may have a very patchy distribution. More than 200 larvae were collected in one sample in phosphorite sand at a depth of 964 ft (294 m) east of Cape Romain, South Carolina.

FEEDING ECOLOGY AND DIET

Feeds on microalgae and bacteria.

REPRODUCTIVE BIOLOGY

Sexual reproduction with reduced postlarvae. The postlarval stage is very short and the cuticle consists only of a thin membrane without scalids. Therefore, it looks as if the Higgins larva molts directly into a mature adult. This species may also have an asexual life cycle with parthenogenetic neotenous larvae.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

Resources Books

Kristensen, Reinhardt M. "Loricifera." In Microscopic Anatomy of Invertebrates. Vol. 4, Aschelminthes, edited by F. W. Harrison and E. E. Ruppert. New York: Wiley-Liss, 1991.

Periodicals

Higgins, R. P., and R. M. Kristensen. "New Loricifera from Southeastern United States Costal Waters." Smithsonian Contributions to Zoology 438 (1986): 1-70.

Kristensen, R. M. "Loricifera, A New Phylum with Aschelminthes Characters from the Meiobenthos." Zeitschrift für Zoologische Systematik und Evolutionsforschung 21 (1983): 163-180.

-. "An Introduction to Loricifera, Cycliophora, and

Micrognathozoa." Integrative and Comparative Biology 42 (2002): 641-651.

Kristensen, R. M., and Y. Shirayama. "Pliciloricus hadalis (Pliciloricidae), A New Loriciferan Species Collected from the Izu-Ogasawara Trench, Western Pacific." Zoological Science 5 (1988): 875-881.

Todaro, M. A., and R. M. Kristensen. "A New Species and First Report of the Genus Nanaloricus (Loricifera, Nanaloricida, Nanaloricidae) from the Mediterranean Sea." Italian Journal of Zoology 65 (1998): 219-226.

Iben Heiner, MSc Martin Vinther Sßrensen, PhD Reinhardt Mßbjerg Kristensen, PhD

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