Laticorophium baconi (Shoemaker, 1934) (Crustacea: Amphipoda: Corophiidae: Corophiini): first record in European marine water

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BioInvasions Records (2019) Volume 8 Article in press
Gouillieux and Sauriau (2019), BioInvasions Records (in press)1
CORRECTED PROOF
Research Article
Laticorophium baconi (Shoemaker, 1934) (Crustacea: Amphipoda:
Corophiidae: Corophiini): first record in European marine waters
Benoit Gouillieux1,* and Pierre-Guy Sauriau2
1Université de Bordeaux, UMR 5805, Station Marine d’Arcachon, 2 rue du Professeur Jolyet, F-33120 Arcachon, France
2LIENSs, Littoral, Environnement et Sociétés, CNRS, La Rochelle Université, UMR 7266, 2 rue Olympe de Gouges, F-17000, La Rochelle, France
Author e-mails: benoit.gouillieux@u-bordeaux.fr (BG), pierre-guy.sauriau@univ-lr.fr (PGS)
*Corresponding author
Abstract
Laticorophium baconi (Amphipoda, Corophiidae) was recorded for the first time in
European marine waters from buoy fouling communities at the Sant Carles de la
Ràpita marina (Alfacs Bay, Eastern Mediterranean Spanish coast). Presence of
juveniles, adult males, brooding and ovigerous females were indicative of a well-
established population. An entire description of the species, together with a
dichotomous key to Corophiini genera characterized by urosome segments fused
with uropod 1 ventrally inserted, are provided. This record supports the view that
L. baconi may have been overlooked and/or potentially confused with other
Corophiini species such as Apocorophium acutum in previous studies.
Key words: fouling community, dichotomous key, Spanish coast, Mediterranean Sea
Introduction
Corophiini Leach, 1814 are generally tube-dwellers amphipods present in
various marine, estuarine and freshwater environments where they colonize
diverse sandy- to muddy-bottom habitats and are sometimes found as
epibionts on epifauna species such as bryozoans, hydrozoans, macroalgae,
and bivalves; some species even reside as specialized commensals, although
others are cosmopolitan (Shoemaker 1934; Williams and McDermott 2004;
Bousfield and Hoover 1997). Bousfield and Hoover (1997) deeply overhauled
the Corophiini tribe by describing 12 new genera and many new species.
Their identification key was and remains largely used around the world.
However, examination of the original descriptions of some Corophiini
species has revealed some mistakes, e.g., for the genus Monocorophium
Bousfield and Hoover, 1997. An update, recently proposed by Gouillieux
and Massé (2019), supported the view that meticulous observation of this
complex tribe is still a challenging task, as is recognizing species properly
and characterizing their ecology (Gouillieux 2019).
Along the northeastern Atlantic European coast, Noël (2011) reported
the introduction of four Corophiini species for the period 1930–1965
(Chelicorophium curvispinum (G.O. Sars, 1895); Corophium multisetosum
Citation: Gouillieux B, Sauriau P-G
(2019) Laticorophium baconi (Shoemaker,
1934) (Crustacea: Amphipoda:
Corophiidae: Corophiini): first record in
European marine waters. BioInvasions
Records 8 (in press)
Received: 23 April 2019
Accepted: 11 July 2019
Published: 4 September 2019
Handling editor: Karolina Bącela-
Spychalska
Thematic editor: Amy Fowler
Copyright: © Gouillieux and Sauriau
This is an open access article distributed under terms
of the Creative Commons Attribution License
(Attribution 4.0 International - CC BY 4.0).
OPEN ACCESS.

First record of Laticorophium baconi in European waters
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Stock, 1952; Monocorophium acherusicum (Costa, 1853) and M. sextonae
(Crawford, 1937)) although only one new introduction, i.e. M. uenoi
(Stephenson, 1932), was recorded during the last decade (Faasse 2014).
This last introduction was thought to be linked to aquaculture in shellfish
ecosystems where the species was recorded, i.e. Yerseke in the Oosterschelde,
The Netherlands (Faasse 2014) and Arcachon Bay, Southwestern France
(Gouillieux and Massé 2019), as already reported for many other non-
indigenous species (NIS) by Goulletquer et al. (2002) and Noël (2011)
along the Atlantic coasts.
The Mediterranean Amphipoda fauna has been extensively studied for a
long time (e.g. Bellan-Santini et al. 1982). However, knowledge about NIS
Corophiidae fauna appears to be not uniform throughout the entire
Mediterranean. Most of the NIS introductions into Spanish coasts were
linked to shipping (Nunes et al. 2014); indicating that in European waters,
as well as in the world, the main introduction factor of NIS differs
depending on local and regional socio-economic activities. According to
the most up-to-date reviews (Zenetos et al. 2017; Galil et al. 2018), there are
no NIS Corophiidae in the Mediterranean Sea, although a few Corophiidae
species such as Laticorophium baconi (Shoemaker, 1934) and Monocorophium
uenoi may be good potential invaders due to their ecology and recognized
valid NIS status outside the Mediterranean Sea (Marchini and Cardeccia 2017).
Corophiidae have a relatively small body size, leading to a high risk of
confusion with endemic and/or cryptogenic species. Therefore, directed
sampling efforts devoted to particular artificial habitats or potential vectors
for NIS Corophiidae can be useful in determining species assemblages. A
recent large-scale study of biofouling peracarid crustaceans on boats in
Mediterranean marinas highlighted the potential role of recreational boating
as vectors for NIS and cryptogenic species, including the three Corophiidae
species Apocorophium acutum (Chevreux, 1908), Monocorophium acherusicum
and M. sextonae (Martínez-Laiz et al. 2019).
The Corophiini amphipod, Laticorophium baconi, is herein recorded for
the first time in the western Mediterranean Sea, east coast of Spain. Since
this is the first record of the species from the Mediterranean Sea and
therefore the first record of the genus Laticorophium Bousfield and Hoover,
1997 in European marine waters, an entire description of the species is
provided. It includes a revised Bousfield and Hoover (1997) key to Corophiini
species, which are characterized by urosome segments fused with uropod 1
arising mainly ventrally.
Materials and methods
Study area
The Sant Carles de la Ràpita and Vinarós marinas are located along the
northern Spanish Mediterranean coast within and South to the Alfacs Bay,

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Figure 1. Stations (A) and habitats sampled in Sant Carles de la Ràpita (B) and Vinaròs (C),
Spanish Mediterranean coast. Presence (black star) or absence (black dot) of Laticorophium
baconi (Shoemaker, 1934) is indicated. Photos by P.-G. Sauriau.
respectively (Figure 1). The Alfacs Bay is a microtidal semi-enclosed estuary
at the south side of the Ebro River Delta, from which it receives irrigation
freshwater coming from rice fields and lagoons through discharge channels
located on its northern shore (Camp and Delgado 1987). Benthic habitats
mostly consist of sandy bottoms and seagrass meadows (Pérez and Camp
1986). The Alfacs Bay plays a major economic role due to its large fish and
shellfish raft farming activities, particularly oysters and the mussel Mytilus
galloprovincialis Lamarck, 1819 (Galimany et al. 2011). Marine waters within
the Sant Carles de la Ràpita marina are silty, leading to the development of
fouling communities adapted to estuarine conditions; although in the
Vinaròs marina, fouling of pontoons was composed by typical clear marine
water species.
Material examined
Fouling communities from buoys and pontoons, where recreational boats
were moored, were collected by hand from ropes hanging in both marinas
and immediately preserved in 95% ethanol. Laticorophium baconi specimens
were subsequently examined with a Nikon SMZ 25 stereomicroscope and a

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Nikon Eclipse E400 microscope with up to 112,5 and 400x magnifications
(and transmitted light) respectively. Body length (BL) was measured with
NIS-Elements Analysis software from the anterior margin of head to the
posterior end of telson. For Scanning Electron Microscope (SEM) studies,
specimens were dehydrated in a graded ethanol series, critical point dried,
sputter coated with gold and examined with a Hitachi TM3030Plus
scanning electron microscope. More than 50 specimens were deposited in
the Muséum National d’Histoire Naturelle (MNHN, Paris).
Results
In the Vinarós marina, the fouling fauna collected from under the pontoons
was composed of typical marine water species, mainly Mytilus sp. Linnaeus,
1758; Serpulidae Rafinesque, 1815 and Clavelinidae Forbes and Hanley,
1848. No specimens of Laticorophium baconi were collected, but individuals
of the isopod Paranthura japonica Richardson, 1909 and the amphipods
Caprella scaura Templeton, 1836; Elasmopus rapax Costa, 1853; Lysianassa
ceratina (Walker, 1889) and Quadrimaera inaequipes (A. Costa in Hope,
1851) were collected. In the Sant Carles de la Ràpita marina, which has much
more silty waters, more than 300 specimens of Laticorophium baconi were
collected from a buoy covered with hydroids and red algae; L. baconi was
the main amphipod species in the sample. Other crustacean species were
also collected (i.e., the isopod Paranthura japonica and the amphipods
Caprella scaura, Elasmopus brasiliensis (Dana, 1855) and E. rapax).
Systematics
Family Corophiidae Leach, 1814
Subfamily Corophiinae Bousfield and Hoover, 1997
Genus Laticorophium Bousfield and Hoover, 1997
Laticorophium baconi (Shoemaker, 1934)
Corophium baconi Shoemaker 1934: 356 (original description), fig. 1.—1949: 82, figs. 5g, h.—
Crawford 1937: 626.—Barnard 1969: 101.—1970: 100, fig. 53.— 1971: 59, fig. 26b.—Otte 1975:
11, fig. 8.—Hirayama 1986: 472, figs. 12–14.—Barnard 1979: 24.—Barnard and Karaman 1991:
185. —Ishimaru 1994: 35.
Laticorophium baconi Bousfield and Hoover 1997: 126, figs. 37.—Lecroy 2004: 462, fig. 425.—
Chapman 2007: 573, figs. 255U, 269G, 270L-N
Doubtful Laticorophium baconi Bousfield and Hoover 1997: 126, figs. 36.—Valério-Berardo and
De Souza 2009: 61, fig. 4.
Material examined: San Carles de la Ràpita, Spain, 40°36.933′N; 0°35.659′E,
subtidal, on mooring buoy (Figure 1), col. Sauriau, P.-G., 05/05/2018,
MNHN-IU-2016-3402 to MNHN-IU-2016-3405.
Description based on male BL = 2.47 mm and female BL = 2.73 mm,
illustrations from supplementary material.
Head (Figures 2E, 3B) rostrum short, broad, not exceeding lateral head
lobes; eyes developed. Male (Figure 2) antenna 1 peduncle articles sparsely

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Figure 2. Laticorophium baconi (Shoemaker, 1934), male specimens from Sant Carles de la Ràpita,
Spain, 5/vi/2018. (A) Lateral view; (B) antenna 1 peduncle article 1 inner view; (C) antenna 2
peduncle article 4 (end) and 5 inner view from male BL = 1.79 mm; (D) antenna 2 peduncle
article 4 (end) and 5 inner view from male BL = 2.54 mm; (E) head dorsal view; (F–G) antenna 2
anteroventral view. Scale bars: (A): 1 mm; (B–G): 0.1 mm. Photos by B. Gouillieux.
setose, peduncle article 1 with 3 robust setae on ventral margin, proximal
could be slightly curved, and 2 robust setae on proximal dorsomedial
margin; peduncle article 2 shorter in length to article 1 without robust
setae; peduncle article 3 the shorter; flagellum with 4 articles, second article
the longest, second and third articles with 1 distal aesthetascs. Male
antenna 2 pediform; peduncle article 3 almost rectangular with a ventrodistal
pair of robust setae; peduncle article 4 longer than article 5, distal
ventromedial corner with 1 short and 1 long acute process and 2 robust
setae on proximal part of ventromedial margin; peduncle article 5 with 1 acute
ventromedial and 1 distal falcate process; flagellum short and 3-articulate,
distal article with 2 distal robust setae. Female antennae (Figure 3) as in
males, except for antenna 2 peduncle article 4 slender, without process and
with 3 single robust setae on ventral margin; peduncle article 5 without
process or robust setae.

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Figure 3. Laticorophium baconi (Shoemaker, 1934), female specimens from Sant Carles de la
Ràpita, Spain, 5/vi/2018. (A) Lateral view; (B) head dorsal view; (C) antenna 1 peduncle article 1
inner view; (D) antenna 2 peduncle article 4 (end) and 5 inner view. Scale bars: (A): 1 mm; (B–D):
0.1 mm. Photos by B. Gouillieux.
Figure 4. Laticorophium baconi (Shoemaker, 1934), specimens from Sant Carles de la Ràpita,
Spain, 5/vi/2018. (A) Mandible; (B) lower lip; (C) maxilliped; (D) maxilla 1; (E) maxilla 2.
Scale bars: (A–C, E): 0.1 mm; (D): 0.05 mm. Photos by B. Gouillieux.
Mouthparts (Figure 4): Mandible molar process with 1 long seta; palp
article 1 distal margin produced distally, with 1 long pinnate seta (type P5
in Hirayama 1987b). Maxilla 1 palp exceeding outer plate, distal margin
with 7 robust setae; outer plate with 7 robust setae. Maxilla 2 inner plate with

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facial and apical plumose setae, outer plate with a row of apical plumose
setae and many setules along outer margin. Maxilliped inner plate short,
not broad, with distolateral plumose setae; outer plate with 10 plumose
setae along inner and distal margin; palp 4-articulate, articles 2 and 3 with
a row of plumose setae on distal and inner margins, article 4 with 1 distal
strong robust seta.
Gnathopod 1 parachelate; coxa anterior margin acute, with 3 anterodistal
plumose setae and 5 dorsal simple seta; basis slender, length 3.5 X breadth,
with 1 simple seta on posterodistal margin; ischium with many plumose
setae on posterodistal margin; merus subtriangular, subequal in length to
ischium, with 3 posterodistal plumose setae; carpus length 2 X breadth,
with 1 anterior and 3 anterodistal simple setae and a row of plumose along
posterior margin; propodus subequal in length to carpus, with simple setae
along posterior margin, 1 robust seta on palmar margin, palmar margin
serrate; dactylus tip little exceeding palm, with 1 tooth on flexor margin
(Figure 5A). Gnathopod 2 simple; coxa anterior margin acute, with 1 simple
seta on distal margin; basis broad, length 1,5 X breadth, with 1 posterordistal
and 1 anterodistal simple setae; ischium subrectangular, short, with 1 simple
seta on posterodistal corner; merus with a row of long plumose setae along
posterior margin; carpus subtriangular with 6 posterodistal long plumose
setae; propodus 2 X longer than carpus, with 2 simple setae on anterior
margin and a cluster of setae on anterodistal corner, 2 simple setae on
posterior margin and a row of 8 plumose setae in proximal part of inner
face; dactylus with 1 tooth on flexor margin (Figure 5B).
Coxae 3–5 with 1 long simple seta on ventral margin. Pereopod 3 coxa
short and subtriangular; basis broad, 1.7 X longer than broad, anterior
margin inflated medially and with 4 simple seta, 1 posterior and 2
posterodistal simple setae; ischium rectangular, with 3 simple seta on
posterodistal corner; merus longer than wide, anterodistal margin slightly
produced, with 1 simple seta on anterior margin, a cluster of simple setae
on anterodistal corner, 2 simple seta on posterior margin and a 2 simple
setae on posterodistal corner; carpus broader than longer with simple and
plumose setae on posterior margin; propodus shorter in length to merus,
with simple and plumose setae on posterior margin and 2 simple setae on
anterodistal corner; dactylus as long as propodus. Pereopod 4 (Figure 5C)
basis broad, length 1.9 X breadth, with 3 simple setae along anterior margin;
others articles similar to pereopod 3, except for number of setae. Pereopod 5
(Figure 5D) coxa bilobed; basis broad, length 1.5 X breadth with 2 anterior
and 5 posterior margins simple setae, 3 posterodistal and 3 anterodistal
simple setae; ischium short, with 2 simple setae on posterodistal margin;
merus with 2 simple setae on posterior margin, and clusters of setae on
antero and posterodistal corners; carpus with 1 and 2 simple seta on antero
and posterodistal corner respectively, 2 clusters of robust setae on outer
face; propodus elongate, with 1 robust and 2 simple setae on anterior margin;

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Figure 5. Laticorophium baconi (Shoemaker, 1934), specimens from Sant Carles de la Ràpita,
Spain, 5/vi/2018. (A) Gnathopod 1 distal end of propodus and dactylus; (B) gnathopod 2 distal
end of propodus and dactylus; (C) pereopod 4; (D) pereopods 5 and 6 with clusters of robust
setae on carpus (white arrows); (E) left epimeral plates 1–3; (F) pleotelson dorsal view with
lateral notches (white arrows); (G) pleotelson ventral view; (H) uropod 3 and telson dorsal
view. Scale bars: (A, B, H): 0.05 mm; (C–G): 0.1 mm. Photos by B. Gouillieux.
dactylus short, with 1 seta on posterior margin. Pereopod 6 (Figure 5D)
coxa bilobed; basis 1.7 X longer than broader, with 5 simple setae and a
row of 5 plumose setae along anterior margin, 2 simple setae along
posterior margin and 3 simple setae on posterodistal corner; ischium with
2 simple seta on posterodistal corner; merus with 2 simple, 3 finely
plumose setae and many setule along posterior margin, 1 simple setae on
anterior margin and a cluster on anterodistal corner; carpus with simple
setae on distal part and 2 clusters of robust setae on outer face; propodus
elongate, with 2 simple setae on posterior margin and 2 simple setae on

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anterodistal margin; dactylus curved anteriorly. Pereopod 7 coxa bilobed;
basis length 1.5 X breadth, with a row of plumose setae on both of margins;
ischium about ½ merus length, with 2 simple setae on anterodistal corner;
merus with 3 and 4 simple setae along anterior and posterior margin
respectively; carpus subequal to merus, with 3 and 5 simple setae on anterior
and posterior margins respectively; propodus elongate, longer than carpus,
with simple setae along posterior and anterior margin, setae on posterior
margin long; dactylus curved anteriorly.
Epimeral plate 1 ovate with 1 posterior simple and 2 ventral plumose
setae; epimeral plate 2 with 2 posterior simple and 2 ventral plumose setae;
epimeral plate 3 subrectangular, hind corner rounded, with 1 posterior
simple and 1 ventral plumose setae (Figure 5E). Pleopods 1–3 similar to
each other; peduncle stout, outer margins with plumose setae, inner
margins with 2 coupling spines; rami with basal articles longer and broader
than distal articles, inner ramus little longer than outer ramus. Urosomites
1–3 (Figure 5F–G) fused, with distinct lateral marginal convex and notch.
Uropod 1 biramous, inserted ventrally; peduncle with 1 outer and 1 interramal
acute teeth, simple proximal and 3 or 4 robust setae along outer margin;
rami with 3 robust setae along outer margin, 1 subapical robust seta on
inner margin, 1 short and 1 very long robust setae on apex. Uropods 2–3
with many setules on posterior and dorsal margins. Uropod 2 biramous,
peduncle with 4 simple setae on outer margin; rami with 2 or 3 simple
setae on outers margins and 1 robust seta on apex. Uropod 3 uniramous;
peduncle slightly produced distally, with 1–2 simple setae on outer and
dorsal margins; ramus ovate, shorter to peduncle, rounded apically, with a
row of simple setae along distal margin. Telson small, rounded apically,
with robust setae tooth-like on the dorsodistal depression (Figure 5H).
Variability
Antenna 1 peduncular article 1 ventral margin with 2 to 4 of robust setae,
with sometimes no left-right symmetry, number of robust setae inversely
proportional to maturity, first(s) one(s) could be curved for young specimens;
proximal dorsomedial margin with 1 or 2 robust setae. Widest male antenna 1
peduncle article 1 and 2, antenna 2 peduncle article 5 and flagellum with
distinctly more and longer simple setae. Male antenna 2 peduncular article
4 and 5 distal teeth size and orientation, as well as peduncular article 5
position, size and orientation of median tooth depending of maturity
(Figure 2C, D, F, G). Gnathopod 1 propodus with or without setae on
anterior margin. Number of simple and plumose setae on pereopods and
epimeral plates 1–3 function of sex and maturity, as well as number of
robust setae composing the clusters on carpus of pereopod 5 and 6.
Urosome lateral notch more or less pronounced.

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Discussion
Laticorophium
The genus Laticorophium was originally composed of only one species:
Laticorophium baconi, present in North American Pacific and Atlantic
coasts, North Asiatic Pacific region, Brazilan waters, and Australian waters
(Hirayama 1986; Bousfield and Hoover 1997; Lecroy 2004; Valério-
Berardo and De Souza 2009; Ahyong and Wilkens 2011). In 2016, Myers
and Nithyanandan described a new Laticorophium species from Sea City
(Kuwait): Laticorophium bifurcatum. They distinguished their species from
L. baconi by (1) the presence of a strong process in male A2 article 5,
(2) the absence of robust setae in male A2 article 4 and (3) the process in
male A2 article 4 opposed to recurved. Size, disposition and orientation of
male antenna 2 article 4 and 5 process is function of maturity, as observed
by Shoemaker (1949), Otte (1975) and in the present paper. Indeed, the
only character which distinguished the two species was the absence of
robust setae in male antenna 2 article 4. Based on this observation,
Laticorophium baconi records by Bousfield and Hoover (1997) and
Valério-Berardo and De Souza (2009) probably refer to L. bifurcatum, but
further study is recommended to confirm this hypothesis.
Laticorophium baconi was originally well described and illustrated by
Shoemaker (1934) from California, North East Pacific Ocean. The species
has since been recorded from the Peru coasts to the Bering Sea, Hawaii,
Gulf of Mexico, Brazil coast and China Sea (Barnard 1970, 1971; Hirayama
1986; Otte 1975; Bousfield and Hoover 1997; Lecroy 2004; Valério-Berardo
and De Souza 2009). The present specimens are in agreement with the
original and subsequent descriptions (Supplementary material Table S1)
except for Bousfield and Hoover (1997) and Valério-Berardo and De Souza
(2009) (see above). The presence of the species in a marina, which had
been observed in other areas (Chapman 2007; see the review by Marchini
and Cardeccia 2017), on a buoy with fouling, suggests its presence is
probably due to shipping. The large sampled population, with brooding
and ovigerous females, implies a well-established population in the marina,
and individuals are potentially present in adjacent marinas. Due to its
resemblance with the cosmopolitan species Apocorophium acutum
(Chevreux, 1908), with urosome segments fused, uropod 1 inserted
ventrally and male antenna 2 process, the two species can be easily
confused, and misidentifications may have been done in previous studies.
Laticorophium baconi was previously considered as a species of the open
sea (Barnard 1971), but has been sampled on mussel beds and on metal
panels which had been immersed (Hirayama 1986). In the present study,
L. baconi was recorded with hydroids and red algae on a buoy in a silted
marina situated in a bay, whereas in Vinaròs marina, an open sea marina,
no specimens were recorded. The absence of L. baconi in Vinaròs marina

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could be explained by the difference in habitat, or due to non-introduction
of the species in this area for the moment. A monitoring of Corophiini
species in the adjacent marinas to San Carles de la Ràpita would therefore
be appropriate to follow the spread of L. baconi in Spanish waters, and
therefore in other European waters (see the recent study by Martínez-Laiz
et al. 2019 across the Mediterranean Sea).
Tribe Corophiini
Bousfield and Hoover (1997) provided a revision for the tribe Corophiini.
They described many new genera and species and proposed a key to world
genera based on type species. The record of Laticorophium baconi on the
Mediterranean coast of Spain led to studying the species characterized by
urosome segments fused with uropod 1 arising mainly ventrally:
Apocorophium Bousfield and Hoover, 1997, Hirayamaia Bousfield and
Hoover, 1997, Laticorophium and Lobatocorophium Bousfield and Hoover,
1997. Lobatocorophium can be easily distinguished from the other genera
by a grossly enlarged uropod 2, and Laticorophium by gnathopod 2 dactylus
with one tooth on the flexor margin and a urosome with the lateral margin
notched. Apocorophium and Hirayamaia are two close morphological genera.
The genus Hirayamaia is represented by three species: H. hongkongensis
(Hirayama, 1986), H. mortoni (Hirayama, 1986) (type species) and H. tridentia
(Hirayama, 1986). Following the Bousfield and Hoover (1997) key,
Hirayamaia can be distinguished from Apocorophium by having straight or
slightly indented (versus convex) urosome lateral margins, a gnathopod 2
propodus with minute palm and cusp (versus propodus lacking palm or
cusp), and a dactylus with 1 (2) tooth on the flexor margin (versus 2–4
teeth). Unfortunately, H. hongkongensis is characterized by convex urosome
lateral margins, while H. tridentia has a dactylus with three teeth on the
flexor margin. The morphology of the urosome margin (i.e., between
straight and slightly convex) can sometimes be subjective, whereas the
dactylus tooth is a relatively stable character within a species: without /
with one / with two or more teeth. H. tridentia presents one tooth on the
gnathopod 2 dactylus flexor margin and uropod 2 has rami that are
marginally not bare (vs bare in Hirayamaia genus diagnose). Due to these
two morphological characters which are closer to Apocorophium than
Hirayamaia diagnoses, we propose to change Hirayamaia tridentia to
Apocorophium tridentia and modify the Bousfield and Hoover (1997) key
for Corophiini species characterized by urosome segments fused with
uropod 1 arising mainly ventrally as follows:
10. Uropod 2 large, broad, larger than uropod 1 (Figure 6A) ........................
.........................................................................................Lobatocorophium
— Uropod 2 relatively inconspicuous, distinctly smaller than uropod 1
(Figure 6B) .................................................................................................. 11

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Figure 6. A, B, E: pleotelson, dorsal view; C, D: gnathopod 2 distal end of propodus and
dactylus. (A) Lobatocorophium lobatum (Hirayama, 1987), after Hirayama 1987a; (B–C)
Laticorophium baconi (Shoemaker, 1934), specimen from Sant Carles de la Ràpita, Spain,
5/vi/2018; (D–E) Hirayamaia mortoni (Hirayama, 1986), after Hirayama 1986.
11. Gnathopod 2 dactylus with 1 tooth on flexor margin (Figure 6C) ...... 12
— Gnathopod 2 dactylus with 2 or 3 teeth on flexor margin (Figure 6D)
................................................................................................ Apocorophium
12. Urosome lateral margin notched (Figure 6B, black arrow) ......................
............................................................................................... Laticorophium
— Urosome lateral margin smooth (Figure 6E) ......................... Hirayamaia
Acknowledgements
This work was initiated during extensive benthic surveys devoted to alien Decapoda of the
Nouvelle Aquitaine Region (France) project, funded by Agence de l’Eau Adour-Garonne and
Ifremer under the scope of the Water Framework Directive (WFD). BG and PGS were partly
funded by Bordeaux University and the Centre National de la Recherche Scientifique (CNRS),
respectively. Special thanks are due to F. Aubert, L. Le Guyader and C. Sauriau for technical
and logistic assistance during fieldworks. Authors also thank Karolina Bacela-Spychalska
(University of Lodz), Amy Fowler (George Mason University) and the two anonymous reviewers
for revision of the manuscript.
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Supplementary material
The following supplementary material is available for this article:
Table S1. Main morphological characters for Laticorophium baconi (Shoemaker, 1934) in original and subsequent descriptions and for
Laticorophium bifurcatum Myers and Nithyanandan, 2016.