Description of Gnathophylleptum tellei gen. nov., sp. nov., a remarkable new gnathophyllid shrimp from canary Islands (Crustacea, Decapoda, Caridea)

13 Pages·2001·2 MB·English

by  D'udekem D'acoz, C

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BULLETIN DE L'INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE, BIOLOGIE, 71: 113-125, 2001
BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN, BIOLOGIE, 71: 113-125,2001
Description of Gnathophylleptum tellei gen. nov., sp. nov., a remarkable new
gnathophyllid shrimp from Canary Islands (Crustacea, Decapoda,
Ca~idea)
by Cedric d'UDEKEM d' ACOZ
Abstract is here erected for this remarkable new species, which has
been found by Mr. Arthur TELLE (Gran Canaria). It may be
A new genus Cnathophy/leptum gen. nov. is erected for a highly distinguished by'many characters, the two most conspicuous
characteristic new species of gnathophyllid shrimp from the Canary being the considerable length and slenderness of the second
Islands : Cnathophy/leptum tellei gen. nov., sp. nov. This species, pereiopod, and the complex tridimensional structure of the
which has been found in the coastal waters of Gran Can aria, is unu
third maxilliped.
sually slender for a member of the Gnathophyllidae and possesses
quite distinctive third maxillipeds. The relationship between
Cnathophylleptum and related genera is discussed in detail. An
Systematics
identification key to all gnathophyllid genera is given.
Key-words: Cnathophylleptwn, Gnathophyllidae, Palaemonoidea,
Caridea, Decapoda, shrimp, taxonomy, phylogeny, corneal papilla, Gnathophylleptum gen. nov.
Canary Islands, Eastern Atlantic
TYPE SPECIES
Gnathophylleptum tellei gen. nov., sp. nov.
Resume
ETYMOLOGY
Un nouveau genre Cnathophy/leptum gen. nov. est propose pour The name derives from Gnathophyllum, the type genus of the
une crevette Gnathophyllidae hautement caracteristique des lies
family Gnathophyllidae, and from A£1!1:0£, slender. The
Canaries : Cllathophy/leptum tellei gen. nov., sp. nov. Cette espece
genus is neutral.
qui a ete recoltee dans les eaux c6tieres de Gran Canaria presente
une silhouette singulierement gracile pour une Gnathophyllidae, et
Ia morphologie de ses maxillipedes de Ia troisieme paire est tout a DESCRIPTION
fait particuliere. Les relations entre C!lathophylleptwn gen. nov. et Rostrum moderately long, armed both dorsally and ventrally.
les genres apparentes sont discutees d'une maniere approfondie. Antenna! spine present and well developed. Cornea with well
Une cle d'identification est donnee pQur tous les genres de developed distal papilla, withou.t ocellum. First segment of
Gnathophyllidae.
antennular segment long and narrow, with short styliform
Mots-des: Cnathophy/leptullz, Gnathophyllidae, Palaemonoidea, stylocerite. Basicerite with well developed lateral tooth.
Caridea, Decapoda, crevette, taxonomie, phylogenie, papille cor Scaphocerite narrow. Mandible very small, devoid of palp
neenne, lies Canaries, Atlantique oriental and incisor process. Upper lacinia of maxillula much larger
than palp and lower lacinia. Maxilla fairly small, with well
developed palp, with basal endite entire and reduced to a
Introduction short blunt lobe. First maxilliped very large, with well devel
oped epipod and exopod, well developed palp; basal endite
Our current knowledge of the decapod fauna of Europe and triangular, narrowing gradually towards its tip which is angu
neighbouring areas is usually considered fairly good but is by lar; coxal endite protruding and completely fused to basal
no mean complete. Each year, one or two new species are endite. Second maxilliped unmodified, with well developed
described from the area (D'UDEKEM D' Acoz, 1999), but in epipod. Third maxilliped with well developed exopod; ulti
most cases, these new species are closely related to already mate and penultimate segment somewhat flattened;
described taxa. The discovery of new genus remains excep ischiomerus strongly flattened, with outer face concave;
tional, especially in the coastal waters. So, it was a real sur maximal width of ischiomerus similar to that of basis, these
prise to discover a new shallow-water Canarian two segments being well separated. Carpus of first pereiopod
gnathophyllid shrimp with a spectacular colour pattern and very long and much longer than propodus; dactylus much
not closely related to any member of this family. A new genus shorter than palm. Second pereiopod slender and extremely
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114 CEDRIC D'UDEKEM D' ACOZ
long; carpus longer than merus and about as long as with fused rami consisting of 6 broad segments; long ramus
propodus; dactylus considerably shorter than palm; chela with 6 narrow segments; short ramus with I segment.
toothless. Dactylus of third, fourth and fifth pereiopod robust
Scaphocerite narrow, 3.5 times as long as wide, with lateral
and bifid.
margin slightly concave; lateral tooth nearly reaching tip of
blade; tooth and blade separated by wide space; tip of blade
regularly rounded, and barely oveneaching tip of antennular
Gnathophylleptum tellei gen. nov., sp. nov.
peduncle. Antenna! peduncle short and moderately slender,
(Figs. 1-7)
reaching 0.27 of scaphocerite. Basicerite with well devel
oped sharp tooth.
MATERIAL
Canary Islands, Gran Canaria, Sardina del Norte, Caulerpa Mandible very small, devoid of palp and incisor process;
racenzosa (FORSSKAL) J. AGARDH meadow, under a hand molar process armed with long sharp teeth.
sized stone, 15m depth, SCUBA diving, Arthur TELLE coli.,
Upper lacinia of maxillula much larger than palp and lower
18/I/200 1: I female holotype (collection Institut royal des
lacinia, with double row of stout spines; palp and lower
Sciences Naturelles de Belgique, Brussels, N° I.G. 29411).
lacinia normally developed; lower angle of palp with a
straight spine pointing laterally.
ETYMOLOGY
It is a pleasure to dedicate the species to Mr. Arthur TELLE Maxilla: fairly small, with well developed palp, with basal
who discovered the species. The name is a genitive. endite entire and reduced to a short blunt lobe without setae.
First maxilliped very large, with large epipod consisting of
DESCRIPTION
two well separated rounded lobes (upper one largest), long
Rostrum straight, slender, moderately long, overreaching
exopod, well developed palp nearly as long as basal endite
mesial margin of first segment of antennular peduncle but
and longer than caridean lobe; basal endite large, triangular,
not reaching tip of distolateral tooth, 0.8 times as long as
narrowing gradually towards its tip which is angular, with
carapace; dorsal margin gently sloping downwards, with 7
very long slender and non-setulose marginal setae; coxal
dorsal teeth spread evenly over its length, posterionnost situ
endite well developed, protruding, bluntly subquadrate and
ated on carapace behind level of orbital margin; ventral mar
completely fused to basal endite, with only one seta in upper
gin horizontal, with 2 ventral teeth on distal 0.3; tip entire
position; caridean lobe with tip broadly rounded, not protrud
and styliform. Posterior 0.9 of carapace unarmed, faintly
ing, much shorter than basal endite.
convex and nearly horizontal. Antenna! spine situated above
inferior orbital angle, sharp and fairly large but not reaching Second maxilliped unmodified, with fairly small unilobed
tip of inferior orbital lobe. Pterygostomian area bluntly trian epipod and with very long exopod.
gular, overreaching tip of antenna! spine. Third pleonite
Third maxilliped without arthrobranch, without epipod, with
moderately convex in lateral view. Pleura of first three
long exopod overreaching ischiomerus, with well developed
pleonites rounded; pleura of fourth and fifth pleonites with
lateral plate; ultimate and penultimate segment subequal,
postero-ventral tooth, that of fifth pleonite being quite long.
much shorter than ischiomerus, somewhat flattened but
Posterolateral angle of sixth pleonite with a sharp tooth. Dor
much longer than broad; penultimate segment with an outer
sal length of sixth pleonite 1.6 x as long as fifth. Ratio dorsal
subquadrate distal projection; outer angle of this projection
length I height of sixth pleonite = 1.6. Telson robust, armed
with a tiny but sharp tooth; inner angle with a large blunt
with 2 pairs of strong dorsolateral spines at 0.4 and 0.7 of its
tooth. Ischiomerus flattened and curved both longitudinally
length. Tip of tel son triangular with 2 pairs of long spines, the
(upwards) and laterally, outer face transversally concave and
inner spines being twice as long as outer spines; with a pair of
inner face transversally convex, well developed distal outer
setulose, robust short setae between the inner teeth; with 2
tooth, low triangular median projection on tip of inner face;
pairs of short thin non-setulose setae, both situated between
outer border broadened (rounded in cross section); mesial
the inner spines and the setulose setae.
border thin with a row of spines. Ischiomerus and basis quite
Eye large, oveiTeaching stylocerite; cornea considerably distinct (not fused), with maximal width similar, but proxi
shorter than stalk, with dorsal surface slightly convex, with mal part of ischiomerus narrower than tip of basis.
ventral surface strongly convex, and bearing a well devel
oped distal papilla at the confluence of the dorsal and ventral First pereiopod with sparse setae; cutting edges of chela
surfaces; no ocellum. toothless; carpus 1.2 x as long as merus, 1.7 x as long as
propodus; propodus 1.6 x as long as ischium; dactylus 0.33 x
First segment of antennular peduncle very narrow, 3 times as
as long as propodus; carpus 6.2 x as long as wide.
long as wide, with a long and sharp distolateral tooth slightly
overreaching second segment, with well developed Second left pereiopod extremely long and slender, with
ventromesial tooth reaching tip of stylocerite, with short but sparse setae; cutting edges of chela toothless; merus over
sharp stylocerite reaching 0.4 of first segment (distal tooth reaching short ramus of upper antennular flagellum; merus
included). Second and third segments of antennular peduncle 1.1 x as long as ischium; carpus 1.3 x as long as merus, 0.9 x
subequal, slightly longer than broad, 0.2 x as long as first as long as propodus; dactylus 0.27 x as long as propodus;
segment (distal tooth included). Upper antennular flagellum carpus 7.0 x as long as wide. Second right pereiopod lacking.
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Description of Gnathophylleptum tellei gen. nov., sp. nov. 115
Fig. I. Gnmhophyl/eplum Lellei gen. nov., sp. nov. Shrimp in lateral view. Scale bar 3.0 mm.
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116 CEDRIC D'UDEKEM D'ACOZ
Fig. 2. Gnathophy/leplum lellei gen. nov., sp. nov. Anterior part of shrimp in dorsal view. Scale bar 3.0 mm
Last three pereiopods morphologically similar, although P3 with an anterior V-shaped marking pointing posteriorly; each
propodus < P4 propodus < P5 propodus, long, fairly robust branch of the "V" made by a row of white dots on a blood red
=
(P3 merus 5.5 x as long as wide), with sparse setae; background; branches of "V" arising from anterior lower
propodus > merus > ischium >carpus >dactylus; propodus part of carapace and dorsally converging at anterior 0.25 of
with 4 widely spaced small spines on distal 0.6 of flexor bor carapace midline; a few white dots within the space com
der; dactylus short and robust, with terminal unguis and prised between the "V" and the anterior part of the carapace.
sharp triangular accessory tooth on flexor border; anterior Posterior 0.2 of carapace with a dorsal transverse stripe made
border of accessory tooth perpendicular to flexor border of up of white dots on a whitish pink background. Third
tem1inal unguis. pleonite with a large dorsal semi-circular spot, anteriorly
rounded and posteriorly straight, made up of white dots on a
whitish pink background. Space between the transverse
COLOUR PAITERN (ON THE BASIS OF COLOUR SLIDES)
stripe and the semi-circular spot, as well as dorsal part of
Most parts of body blood red with faintly contrasted dots of a fourth and fifth pleonites made of a paler red than the rest of
darker red. Rostrum transparent, tinged with white. Carapace the body. Sixth pleonite and tail fan transparent with a few
I I
Description of Gnathophylleptwn tellei gen. nov., sp. nov. 117
A
D
c
Fig. 3. Gnathophylleptum re/lei gen. nov., sp. nov. A, left eyestalk in lateral view; B, first left antenna; C, second left antenna; D, telson.
Scale bar: A, B, C 1.0 mm; D 0.68 mm.
discrete milky-white dots. Eyestalks transparent with white parent with a few white dots; transition between the red and
dots and a few faint red marks; cornea grey. Antennulae and the transparent part abrupt. Pleopods transparent, with a few
antennae transparent with a few white dots. Proximal 0.4 of milky-white dots.
third maxilliped red; distal 0.6 transparent with white dots.
Proximal part of pereiopods up to tip of ischium red; distal Size.- Carapace length= 2.8 mm; total length= 12 mm.
part of pereiopods from basal part of merus onwards trans-
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118 CEDRIC D'UDEKEM D'ACOZ
Ecology palp and. the lower lacinia, but these size differences are
much more pronounced in Gnathophyllwn. In
The unique specimen of Gnathophylleptum tellei gen. nov., Gnathophylleptwn gen. nov., the lower distal spine of the
sp. nov. studied has been found in a Caule1pa racemosa palp is directed outwards, while in Gnathophylhun it is
(FORSSKAL) J. AGARDH meadow, under a stone, at 15 m curved inwards.
depth. According to Mr. Arthur TELLE who collected it dur
The basal endite of the maxilla of Gnathophylleptum. gen.
ing SCUBA diving, there was no evidence of any association
nov. forms a reduced but distinct blunt protrusion, while in
between the shrimp and any other organism. However, its
Gnathophyllum, it is absent.
strongly modified mouthparts suggest a specialized feeding
habit. In Gnathophylleptum gen. nov., the exopod and the endopod
of the first maxilliped are close to each other, while they are
separated by a large space in Gnathophyllum. In
Morphological affinities of Gnathophylleptum gen. nov. Gnathophylleptum gen. nov., the tip of the caridean lobe is
not protruding ; in Gnathophyllum it is always long. In
The Gnathophyllidae are a small family of palaemonoid Gnathophylleptum gen. nov., the palp considerably over
shrimps, which have a highly specialized morphology, espe reaches the caridean lobe and nearly reaches the tip of the
cially their mouthparts, and which are usually brightly col basal endite, while in Gnathophyllum it is shorter than the
oured. Gnathophylleptum gen. nov. shows some affinities, caridean lobe· and is much shorter than the basal endite. In
especially regarding the morphology of the second Gnathophylleptum gen. nov., the basal endite is triangular,
maxilliped, with one member of the very heterogenous genus gradually narrowing towards tip which is angular ; in
Gnathophylloides SCHMITT, 1933: G. mineri SCHMITT, 1933. Gnathophyllwn, it is elliptic with a rounded tip. In
However, the latter species can be distinguished at first Gnathophylleptwn gen. nov., the coxal endite is large, while
glance from Gnathophylleptum gen. nov. by its very short it is quite small in Gnathophyllum.
and robust walking legs, whose dactylus are devoid of acces
In Gnathophylleptwn gen. nov., the second maxilliped shows
sory tooth. The general appearance of Gnathophylleptum
little specialization in contrast with Gnathophyllum. In
gen. nov. is similar to that of the very homogenous genus
Gnathophylleptum gen. nov., half of the exopod overreaches
Gnathophyllum LATREILLE, 1819, but a closer examination
the endopod (tenninal setae not considered), while in
reveals profound differences, and both genera are obviously
Gnathophyllum, the exopod and the endopod are subequal ;
not closely related. A detailed comparison between
the proximal part of the endopod is considerably broadened
Gnathophylleptum gen. nov. and Gnathophyllum is given
in Gnathophyllwn, but not so in Gnathophylleptwn gen. nov.
here below, as well as a key to all gnathophyllid genera. The
; in G11.athophylleptum gen. nov., the ultimate segment is
data on the morphology of Gnathophyllum are based on a
smaller than the antepenultimate and both segments have a
Sicilian Gnathophyllum elegans (RISSO, 1816) which has
normal morphology ; in Gnathophyllum, the ultimate seg
been dissected and on the detailed illustrated accounts of
ment is very large and very elongate in a downwards direc
HOLTHUIS (1949), MANNING (1963), CHACE & FULLER
tion, and is much larger than the antepenultimate segment
(1971), TITGEN (1989) and MANNING & CHACE (1990).
which is reduced.
Specifically, the following differences are apparent between
Gnathophylleptum gen. nov. and Gn.athophyllum. In Gnathophylleptum gen. nov., the third maxilliped has 2
distal teeth on the outer border of its penultimate segment;
In Gnathophylleptwn gen. nov., the rostrum is slender, espe
these teeth are lacking in Gnathophyllum. In
cially in its distal part, while in Gnathophyllwn it is fairly
Gnathophylleptwn gen. nov., the ischiomerus is quite distinct
robust.
from the basis, while these segments are fused and scarcely
In Gnathophylleptum gen. nov., the pleura of the fourth and distinct in Gnathophyllum. In Gnathophylleptum gen. nov.,
the fifth pleonites have a posterior tooth, that of the fifth be the outer face of the ischiomerus is strongly concave in the
ing very sharp. In Gnathophyllum, the fourth pleonite is transverse plane, while it is slightly convex in
regularly rounded and the fifth is rounded or bluntly angular. Gnathophyllum. In Gnathophylleptwn gen. nov., the outer
border of the ischiomerus is thickened, whilst it is thin in
In Gnathophylleptum gen. nov., the eyestalks are more slen
Gnathophyllum. In Gnathophylleptum gen. nov., the outer
der, with a more conical cornea than in Gnathophyllwn. In
border has a strong distal tooth which is absent in
Gnathophylleptum gen. nov., the first segment of the
GJrathophyllunr.
antennular peduncle is very slender with a short stylocerite,
while it is very broad with a very long stylocerite in The second left pereiopod in Gnathophylleptwn gen. nov. is
Gnathophyllum. The scaphocerite in Gnathophylleptum gen. extremely long and slender, with a carpus nearly as long as
nov. is slender, while it is very broad in Gnathophyllum. the propodus, and without teeth on the cutting edges of its
chela (the second right pereiopod is Jacking in the unique
No incisor process is present on the mandible of
specimen examined); in Gnathophyllum, the second left
Gnathophylleptum gen. nov., whilst in Gnathophyllum, it is
pereiopod is much shorter, not especially slender, has its car
either absent or vestigial, depending on the species.
pus much shorter than propodus, and the cutting edges of its
Both Gnathophylleptum gen. nov. and Gnathophyllum. have chelae are toothed.
the upper lacinia of the maxillula considerably larger than the
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Description of Gnathophylleptum tellei gen. nov., sp. nov. 119
E
Fig. 4. Gnathophy/!eptum tel lei gen. nov., sp. nov. A, right mandible; tip of right mandible; C, first right maxilla; 0, palp of first right
maxilla; E, second right maxilla; F, first left maxilliped; G, second left maxilliped. Scale bar: A, C, E, F, G 0.50 mm; B 0.083 m111;
0 0.17111111.
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120 CEDRIC D'UDEKEM D' ACOZ
c
Fig. 5. Gnathophylleptum tell ei gen. nov., sp. nov., third left maxilliped. A, lateral outer view; B, lateral inner view; C, facial inner view.
Scale bar 1.0 mm.
II
Description of Gnathophylleptum tellei gen. nov., sp. nov. 121
B
Fig. 6. Gnathophyl/eptwll rellei gen. nov., sp. nov., A, first left pereiopod; B, second left pereiopod; C, dactylus of third left pereiopod.
Scale bar: A, B 1.0 mm; C 0.17 mm.
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122 CEDRIC D'UDEKEM D' ACOZ
Fig. 7. Gnathophy/leptumtellei gen. nov., sp. nov., A, third left pereiopod; 8, fourth left pereiopod; C, fifth left pereiopod. Scale bar 1.0
mm.