Tardigrades of North America: Archechiniscus biscaynei,
nov. sp. (Arthrotardigrada: Archechiniscidae), a Marine
Tardigrade from Biscayne National Park, Florida
William R. Miller, Tiffany Clark, and Cullen Miller
Southeastern Naturalist, Volume 11, Issue 2 (2012): 279–286
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2012 SOUTHEASTERN NATURALIST 11(2):279–286
Tardigrades of North America: Archechiniscus biscaynei,
nov. sp. (Arthrotardigrada: Archechiniscidae), a Marine
Tardigrade from Biscayne National Park, Florida
William R. Miller1,*, Tiffany Clark1, and Cullen Miller1
Abstract - During the 2010 National Park Service BioBlitz at Biscayne National Park,
Homestead, FL, barnacles were collected from a submerged mangrove log near the Park
headquarters. From the washings of the crushed barnacles, Archechiniscus biscaynei nov.
sp. was extracted. This new species can be distinguished by its lack of a median cirrus, its
large peduncles at the base of the external claws, the rounded cephalic clava between the internal
and external cephalic cirri, a club-shaped papilla above the base of leg IV, and bulbous
papilla just above the claws on the anterior of legs I, II, and III. A table of comparison of characteristics
among the four known species and a key to their identification are provided.
In 1953, while examining washings of barnacles (Cirripedia) from El Salvador
(Central America), Enrich Schultz found a single tardigrade with a unique claw
pattern. The animal had the two external claws attached to the base of the leg
like suborder Echiniscoidea and two internal claws extended on digits or toes like
some Arthrotardigrada. Based on this unique toe-claw structure and the lack of a
median cirrus, Schultz (1953) described the new sub-family Archechiniscinae in
the family Oreellidae in the suborder Echiniscoidea, a new genus (Archechiniscus
Schultz, 1953), and a new species (Archechiniscus marci Schultz, 1953).
Ten years later, Renaud-Debyser (1963) reported the animal from Bimini in
the Bahamas, and in a few years later, Schuster and Grigarick (1966) reported
another single specimen from coral washings from tide pools on Santa Cruz
Island in the Galapagos. While the next year, Renaud-Mornant (1967) collected
specimens from the sandy bottom of Saint-Vincent Bay, New Caledonia.
Ten years passed before Binda (1978) established the new family Archechiniscidae
within the suborder Arthrotardigradea and transferred the new family with
genus Archechiniscus from its previous classification in suborder Echiniscioidea,
family Oreellidae because the internal claws were extended on digits (toes). Another
ten years passed before a second species—Archechiniscus minutus Grimaldi de
Zio and D’Addabbo Gallo, 1987—was described from depths up to 35 m in course
coralliferous debris in both the Adriatic and Ionian Seas around southern Italy. A
decade later, a third species—Archechiniscus symbalanus Chang and Rho, 1998—
was described from barnacles from the Andaman Sea on the coast of Thailand.
Recently, a species of Archechiniscus that was included in a molecular phylogenetic
investigation suggested that Archechiniscus might not be a halechiniscid, but
rather represents a distinct taxon (Jørgensen et al. 2010). This development has led
1Department of Biology, Baker University, Baldwin City, KS 66006. *Corresponding
author - William.Miller@BakerU.edu.
280 Southeastern Naturalist Vol. 11, No. 2
Degma et al. (2011) to place Archechiniscus within Archechniscidae as suggested
by Binda (1978).
Since another decade has again passed, it seems timely to describe the
fourth species of this rarely reported genus. The new species, like A. marci and
A. symbalanus, was extracted from between the plates of barnacles in the intertidal
zone, not the deeper water where A. minutus is found.
Materials and Methods
In early 2010, we were invited by the National Park Service and the National
Geographic Society to attend the fourth annual United States Park Service
BioBlitz held at Biscayne National Park, FL. We collected gravel, sand, and barnacles
from the intertidal zone.
Barnacles were scraped with a putty knife from rocks, concrete pilings, and a
submerged mangrove log in the tidal water of Biscayne Bay and placed into sandwich-
sized plastic bags. The barnacles were crushed in the bag, which punctured
the plastic. Then 50 ml of bottled fresh water were added and the contents washed
into a new bag. This bag was allowed to stand for two hours before sub-sampling.
Five, 2-ml sub-samples of debris from the bottom of the bag were siphoned with
a disposable pipette and examined in a 25- x 50-mm plastic tray with the bottom
painted black. A 20x dissecting microscope was used to search the sub-samples.
Two high-intensity LED lights were arranged, one at 90 degrees and another at 45
degrees to the dish, to give good color and shadow essential to seeing the nearly
transparent marine tardigrades.
The osmotically shocked specimens were extracted with an Irwin loop
and placed directly into a drop of polyvinyl alcohol on a glass slide and
covered with a glass cover slip. After drying for several days, the cover slip was
sealed with clear fingernail polish.
The key in Ramazotti and Maucci (1983) was used to identify the genus, and
the checklist of Degma et al. (2011) was used to confirm that three species had
been described. The original papers for each species were used to compare to the
Two specimens of Echinsicoides sigismundi sigismundi (M. Schultz, 1865)
were found in five samples collected from barnacles attached to rocks and pilings
collected from the visitors harbor on Elliot Key. Three specimens of the Archechiniscus
biscaynei nov. sp. were found in two samples of barnacles removed
from a dead mangrove log submerged near the Visitors Center at Convey Point.
No tardigrades were found in the five sand or gravel samples examined.
Class: Heterotardigrada Marcus, 1927
Order: Arthrotardigrada Marcus, 1927
Family: Archechiniscidae Binda, 1978
Genus: Archechiniscus Schultz, 1953
2012 W.R. Miller, T. Clark, and C. Miller 281
Archechiniscus biscaynei nov. sp.
(Figures 1, 2; Tables 1, 2)
Diagnosis: Archechiniscus with smooth cuticle, cephalic clava a mounded
circle between the small internal and external cirri, large peduncle under external
claws, club-shaped papilla at the base of leg IV, bulbous papilla on anterior
surface of each of legs I, II, 7 III, median cirrus absent, and a short cirri at E.
Description: Measurements of holotype, (paratype 1, paratype 2). Cylindrical
body shape, rounded posterior and narrower rounded anterior end with
protrudable mouth cone. Body length 246.6 μm (198.5 μm, 207.8 μm), width
93.3 μm (74.5 μm, 75.5 μm), eye spots absent. Body segments not apparent, cuticle
colorless and smooth. Internal cirrus 6.5 μm (5.6 μm, 6.7 μm) with annular
refracting organelle (annulus) in expanded base. External cirrus 8.5 μm (7.8 μm,
7.0 μm) with annulus and expanded base. Cephalic clava is low, rounded dome
8.4 μm diameter (6.8 μm, 6.8 μm) with annulus and low protuberance above
cuticle. Secondary clava located equal distance between and below (ventral)
internal and external cirri. Median cirrus absent. Cirri A short 8.3 μm (8.3 μm,
10.3 μm), half the length of expanded base. Primary clava 5.9 μm (5.7 μm, 5.0
μm) club-shaped bulb with annulus arising from same base as cirrus A.
Protrudable mouth cone, terminal to sub-terminal. Buccal tube, stylets, and
pharynx not visible on holotype or paratypes. Cirrus E short, 10.3 μm including
4 μm base (12.9 μm, 10.8 μm). Club-shaped papilla with annular refracting
organelle on dorsal lateral surface at base of leg IV, 4.5 μm (4.3 μm). Stubby,
non-telescopic legs, sensory spine on leg I absent. Bulbous papilla just above
claws on anterior of legs I, II, and III. Internal claws unbranched, sickle shaped
uncus 6.3 μm long (6.6 μm, 6.0 μm) with thin or fine accessory points on 6.0 μm
digits or toes. External claws, 7.5 μm (6.1 μm, 6.8 μm) with stout basal spur, 2.4
μm (2.1 μm, 2.1 μm) with large rectangular peduncles at base. Thin membranous
sheaths on internal claws visible.
Female gonopore with six folds located about 10 μm anterior to anus, male
gonopore round 3 μm opening only 3 μm from anus. Slit like anus, 6 μm, surrounded
by fan of folds on sides and posterior end. Seminal receptacles long, thin
(2 μm wide) tubes exiting ventro-laterally anterior to legs IV.
Holotype: Female, slide number B004515 under accession number BISC-271
at the South Florida Collections Management Center, Everglades National Park,
Paratypes: Two males, slide numbers B004514 and B004516 under accession
number BISC-271 at the South Florida Collections Management Center, Everglades
National Park, Homestead, fl33034.
Etymology: The proposed specific name, biscaynei was chosen to commemorate
the location of discovery of the specimens, Biscayne National Park, Homestead,
Type Locality: A submerged mangrove log in inter-tidal zone in front of the
Dante Fascell Visitor Center, Convoy Point, Biscayne National Park, Homestead,
FL, latitude 25.46503, longitude -80.33479.
Differentiation: The new species is easily differentiated from other species
of Archechiniscus by the lack of median cirrus, the peduncles at the base of the
282 Southeastern Naturalist Vol. 11, No. 2
external claws, the round cephalic clave equal distance between the cephalic
cirri, the club-shaped papilla above leg IV, and the bulbous papilla on the front
of each leg (Tables 1, 2). The new species differs from A. minutus by having
Figure 1. Archechiniscus biscaynei nov. sp., A. Body, B. Legs IV, C. Claws leg IV, D. Leg
II, E. Head segment. a = opening for seminal receptacle, b = bulbous leg papilla, c = gonopore,
d = anus, e = peduncle, f = spur of external claw, g = accessory points of internal
claw, h = lateral cirrus A, i = external cirrus, j = secondary clava, k = internal cirrus, l =
primary clava, m = annular refracting organelle.
2012 W.R. Miller, T. Clark, and C. Miller 283
peduncles under the external claws, and a club-shaped posterior clava. It differs
from A. symbalanus by the absence of the small median cirrus and the absence
Figure 2. Archechiniscus biscaynei nov. sp., A. Lateral cirrus A and primary clava, B.
secondary clava, C. cross section of cuticle, D. male gonopore and anus, E. seminal
receptacle, F. female gonopore and anus, G. club-shaped papilla leg IV, H. lateral cirri
E. fg = female gonopore, h = lateral cirri A, j = secondary clava, l = primary clava, m
= annular refracting organelle, mg = male gonopore, o = anus, p = cuticular pillars, q =
club papilla base leg IV.
284 Southeastern Naturalist Vol. 11, No. 2
of a sensory spine on Leg I. Archechiniscus marci exhibits nine transverse metameric
folds that appear as plates and a cuticle with minute granulation, while
A. biscaynei nov. sp. does not.
Remarks: The holotype female was 22% larger than the paratype males and
other features exhibit similar dimensional differences (see description). This differentiation
might be sexual dimorphism or simply a function of age.
Table 1. Comparison of species of Archechiniscus. NA = not applicable.
Characteristic A. marci A. minutus A. symbalanus A. biscaynei
Body Size (length x width) 198 μm 140 x 55 μm 209 x 64 μm 247 x 93 μm
Eyes Red Present Black Absent
Cuticle Fine dots Fine dots Fine dots Smooth
Transverse metameric folds 9 7 Absent Absent
Median cirrus Absent Absent 2.3 μm Absent
Seminal receptacles NA Long S shaped Long
Sensory spine leg I Absent Absent 2.3 μm Absent
Internal cephalic cirrus 3.8 μm 5.5 μm 4.6 μm 6.5 μm
External cephalic cirrus 4.5 μm 5.5 μm 5.0 μm 8.5 μm
Cephalic clava shape Ring Round Oval Round
Cephalic clava position Under ext cirri Under ext cirri Under ext cirri Between ext
and int cirri
Primary clava 4.5 μm 5 x 2.7 μm 3.8 x 3.2 μm 5.9 μm
Cirrus A 6.4 μm 7.0 μm 5.8 μm 8.3 μm
Buccal tube length NA 27 μm 38.1 x 2.3 μm NA
Stylets Serrated Smooth 30 μm Smooth 28.5 μm NA
Stylet supports Absent Absent Absent NA
Stylet sheath Absent Absent 17.7 μm NA
Furca Rounded Square Rounded NA
Cirrus E 26 μm 8.25 μm 7.3 μm 10.3 μm
Papilla base of leg IV Absent 3.3 μm Present Club 4.5 μm
Anterior papilla, Legs I–III Absent Absent Present Bulbous
Internal claws 6.5 μm 3 μm 5.0 μm 6.4 μm
Internal claws: Accessory pts Absent Small Present Thin or fine
Internal claw and toe (digit) 15.6 μm 8.5 μm 10.4 μm 12 μm
Ext. claws w/ basal spur 7.0 μm 7 μm (3 μm) Small 7.5 μm
Ext. claws w/ peduncles No 4.4 μm 3.5 x 1.9 μm 2 x 2 μm
Retractable claws in sheaths Yes Yes No Yes
Seminal receptacle NA U shaped S shaped S shaped
Female gonopore NA NA 7.3 μm 5.0 μm
Male gonopore NA NA NA 3.0 μm
Table 2. Key to the species of Archechiniscus.
1 Median cirrus absent ..............................................................................................................2
1. Median cirrus present ........................................................................................A. symbalanus
2. Cephalic clava round, at base of external cirri ........................................................................3
2 Cephalic clava round, between and ventral to internal and external cirri .............. A. biscaynei
3. Papilla at base of leg IV, external claws without peduncles ........................................ A. marci
3. Lacking papilla at base of leg IV, external claws with peduncles ............................A. minutus
2012 W.R. Miller, T. Clark, and C. Miller 285
Archechiniscus biscaynei nov. sp. was transparent with bright green ingested
algae in the digestive system. This coloration was in contrast to the bright red
digestive system observed in Echinisoides sigismundi collected from other
barnacles in the same area at the same time. The different colors suggest a noncompetitive
food selection by these two barnacle inhabiting species.
The barnacle habitat is exposed above tide for several hours twice per day. The
compact oval body shape, small appendages, and short stubby legs may be adaptations
that reduce the surface area and limit dehydration compared to animals
with more elaborate body shapes, longer legs, and complex cuticles. However,
this speculative observation warrants further study.
It appears that this family/genus may be distributed in an equatorial pattern: El
Salvador, Bahamas, Galapagos, New Caledonia, Italy, Thailand, and Florida. It
also appears there may be two different habitats utilized by the genus: the intertidal
barnacle and tide pool gravel and the sand and debris in deeper coastal water.
Archechiniscus biscaynei nov. sp., like many marine tardigrades, has been
described from only a few specimens. This underscores our lack of knowledge
about both the diversity and ecology of marine tardigrades and points to the need
and opportunity for further research.
We are grateful to the National Park Service for hosting the 2010 BioBlitz. We wish
to acknowledge the organizational work of Tim Watkins of the National Park Service
and John Francis of the National Geographic Society in making the BioBlitz happen and
providing us the opportunity to explore this unique coastal habitat. The North American
Tardigrade Project was funded under National Science Foundation DEB Grant 0640847.
Finally, we appreciate the support and encouragement of our faculty colleagues Calvin
Cink, Darcy Russell, Charmaine Henry, and Erin Morris at the Department of Biology,
Baker University who make it possible for our undergraduates to participate in authentic
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