Nepinnotheres pinnotheres (Linnaeus, 1758)

Becker, C. & Türkay, M., 2010, Taxonomy and morphology of European pea crabs (Crustacea: Brachyura: Pinnotheridae), Journal of Natural History 44 (25 - 26), pp. 1555-1575 : 1557-1563

Nepinnotheres pinnotheres (Linnaeus, 1758)

( Figure 1D, E, 2A–D , 3A–C )

Cancer pinnotheres Linnaeus, 1758, p 628 , types probably not extant, type-locality: “Habitat in Mari Mediterraneo and Asiatico”; Linnaeus, 1767, p 1040.

Pinnotheres veterum Bosc, 1802, p 243 .

Pinnotheres ascidicola Hesse, 1872 , p 30 –35 [newly synonymized].

Pinnotheres marioni Gourret, 1888, p 186 –187, plate 2 (figures 5–9), plate 4 (figure 6) [newly synonymized].

Pinnotheres pinnotheres: Balss, 1927, p 1022 [new combination]; Atkins, 1954, p 700 –715, figures 8–17.

Nepinnotheres pinnotheres: Manning, 1993, p 150 –170, figures 18–30 [new combination].

A detailed synonymy is presented in Schmitt et al. (1973).

Material examined

Northeast Atlantic. France, Brittany: 13, 1♀ juvenile, host: Ascidia mentula, Morgat , 48°13′N, 4°29′W, hand-collected, 21 March 2007, leg. A. Magdeburg ( SMF 33403– SMF 33406). 13 , 1♀, host: Ascidia mentula , bay of Morlaix, Île le Cerf , le Colombier, 48°36′ N, 3°59′W, 29 March 1994, leg. E. Dumoulin ( SMF 33411) .

Mediterranean. Ligurian Sea: 13, Italian Riviera, Genova, Portofino 44°18.312′N, 9°12.702′E, October 1913, leg. L. Nick ( SMF 5293 ). 23, 1♀, host: “ Phallusia ”, Italian Riviera, Genova, Portofino, 44°18′N, 9°12′E, 17 October 1913, leg. L. Nick ( SMF 5294 ) .

Tyrrhenian Sea: 13, host: “ Cynthia mentula ”, Italy, Campania, 13 March 1912, leg. L. Nick ( SMF 5295) . 1♀, Italy, Isola d’Elba , August 1965, leg. J. Martens ( SMF 5153 ) . 4♀, host: Pinna nobilis, Strait of Bonifacio, Italy, Sardinia, Teresa di Gallura , 41°14′44″N, 9°11′24″E, August 1961, leg. M. Grasshoff ( SMF 4907 ) .

Northern Adriatic Sea , Italy, Trieste: 1♀, Isla Croce, 13 February 1914, leg. O. Löw-Beer, SMF 4925 . 1♀, Isla Croce , 20 July 1969, leg. G. Pilleri ( SMF 9867 ) .

Northern Adriatic Sea, Croatia, Istria: 33, 4♀, 2♀, 1♀ juvenile hard stage, 4♀ ovigerous, Rovinj, Dvije Sestrice, hard bottom dredge, 10 September 1985, leg. RV BURIN ( SMF 31505, SMF 31507, SMF 31509, SMF 34003). 13, Stat. 1 Ku, beam trawl, 05 September 1985, leg. RV BURIN, SMF 31506. 23, Rovinj, west of Crveni otok ( Red Island ), Stat. 5-1, 16 August 1989, leg RV BURIN ( SMF 31513). 83, 1♀, 1♀ juvenile, 13♀ ovigerous, 2.8 nm W lighthouse San Giovanni in Pelago, Stat. Rov 95-10, 45°2.634′N, 13°32.646′E, hard bottom dredge, 05 September 1995, leg. RV BURIN ( SMF 31508). 13, 2♀ juvenile hard stage, 1♀ ovigerous, host: Ascidia mentula , 1 nm SW Banjole, Stat. YU-87/7b-1, 45°3.407′N, 13°35.158′E – 45°3.407′N, 13°35.158′E, beam trawl, 18 September 1987, RV BURIN , leg. D. Krämer ( SMF 33811). 1♀ juvenile stage II, 1♀ juvenile stage III–IV, 2♀ ovigerous, 2 nm N Banjole, Stat. YU-87/7c, 18 September 1987, RV BURIN , leg. D. Krämer ( SMF 33812). 1♀ ovigerous, Rovinj , 1 nm SW Banjole, Stat. YU-87/7b-2, 45°3.407′N, 13°35.158′E – 45°3.407′N, 13°35.158′E, 18 September 1987, RV BURIN , leg. D. Krämer ( SMF 33813). 23, 2♀, 1♀ ovigerous, host: Ascidia mentula , 1 nm SW Banjole, Stat. YU-87/7a-1, 45°3.407′N, 13°35.158′E – 45°3.407′N, 13°35.158′E, 18 September 1987, RV BURIN , leg. D. Krämer ( SMF 33814). 3♀, host: Ascidia virginea, Banjole, Stat. YU-87/3b-1, 45° 3.407′N, 13°35.158′E – 45°3.407′N, 13°35.158′E, 15 September 1987, RV BURIN , leg. D. Krämer ( SMF 33815). 33, host: Ascidia virginea, Banjole, Stat. YU-87/3b-1, 45°3.407′N, 13°35.158′E – 45°3.407′N, 13°35.158′E, 15 September 1987, leg. RV BURIN, SMF 34005 . 13, 1♀ ovigerous, Rovinj , 16 August 1989, leg. RV BURIN ( SMF 31511). 23, host: Halocynthia papillosa, Rovinj, Stat. Rov 05, scuba-diving, 24 August 2005 , leg. C. Becker ( SMF 33806). 2♀, Rovinj ( SMF 5291 ). 33, host: Ascidia mentula, Rovinj , scuba-diving, 16 August 1989 ( SMF 33807). 13, Rovinj, leg. 16 August 1989 ( SMF 31514). 13, Rovinj, Notes: scale bars, 5mm (A–B, D–E, G); 2 mm (C); 10 mm (F); photographs, C. Becker (A–E), S. Tränkner (F–G) .

Notes: scale bars, 2mm (A); 500 µm (B); 250 µm (C)

leg. 1987 ( SMF 31515). 1♀ , Rovinj, leg. 1989 ( SMF 31516). 1♀ , host: Pinna nobilis, Rovinj , beam trawl, December 2003, RV BURIN, leg. D. Brandis ( SMF 33409) .

Levantian Sea: 13 free living, NW-Greece, July 1993, leg. C. d’Udekem d’Acoz, ( SMF 33461) .

Ionian See: 1♀ ovigerous, host: Halocynthia papillosa , Greece, Thesprotia, Syvota , 38°37′N, 20°40′E, 15 July 1993, leg. C. d’Udekem d’Acoz ( SMF 33410). 1♀ ovigerous, host: Halocynthia papillosa , Greece, Crete, Agia Pelagica, “Made”, 35°24′3.41″N, 25°2′1.70″E, scuba-diving, 18 January 2007, leg. C. Becker and M. Schneider, ( SMF 33408) .

Notes: scale bars, 2 mm (A); 1 mm (B); 500 µm (C).

Male

General description ( Figure 2A ). Colour fawn to light brown. Carapace rounded, dorsally convex, strongly calcified, not translucent, without defined regions and lateral teeth. Carapace, as well as whole body surface, especially front, pilose, appearance dull owing to short pappose setae only noticeable under high magnification. Front pronounced, bilobed by narrow median notch. Eyes clearly visible in dorsal view, with bright red colouration in living specimens.

Chelipeds (P1), relative length of articles of walking legs and third maxillipeds consistent with description of female given below. Second and third pair of walking legs (P3, P4) with swimming fringes: two rows of long pappose setae on distal articles. One running dorso-posteriorly on carpus and propodus, one ventro-anteriorly. Shorter pappose setae lining dorsal and ventral margins of all walking legs (P2–P5).

Size of males varies with host, maximum carapace width about 8 mm in specimens from giant Mediterranean pen, Pinna nobilis .

Pleon (abdomen) and sternum ( Figure 2B ). Male abdominal segments clearly separated. Belonging to thoracotremata, male gonopores located on sternum. Pleon narrow, roughly tongue-shaped, general form slightly triangular. Pleon tapering distally with segments 3–5 trapezoidal, every segment somewhat narrower than previous. Pleon broadening in distal part of segment 6 and in rounded telson. Whole outer margin of abdomen fringed with setae, entire surface of pleon pilose with short pappose setae.

First gonopod ( GP 1) ( Figures 2C, D ). Paired copulatory organs, first gonopods, running parallel basally for three-quarters of total length, distal quarter strongly curved towards lateral outside: position of distal tip with opening of ejaculatory canal resulting in angle of about 90° to base. First gonopod slender, slightly flattened dorso-ventrally, gradually tapering distally. Next to long pappose setae on proximal base of gonopod, long simple setae along total length of first gonopod, particularly near its curve.

Female (adult)

General description ( Figure 1D, E, 3A ). Colour fawn to light brown. Carapace subglobular or wider than long, especially in large females. Carapace soft, slightly translucent, surface setose, without defined regions. Front projecting a little, clearly bilobed by median incision. Eyes more or less visible in dorsal view, depending on size of specimen. Eyes with bright red colouration in living specimens. Surface of carapace pilose. Pleon very broad and rounded, covering whole ventral side, coxae of walking legs laterally, reaches buccal region anteriorly. Pleon’s margin fringed with setae. Surface of pleon pilose, with short pappose setae. Juvenile hard stage females before metamorphosis consistent with description of male (except for pleopods).

Carapace width of clearly adult (ovigerous) females from around 5 mm in small females inhabiting ascidians, up to 20 mm in Pinna nobilis .

Chelipeds and walking legs ( Figure 3A, B ). Cheliped, especially palm of chela, rather robust. Cutting edge of palm with one stout triangular tooth on movable finger (dactylus) interlocking into depression on fixed finger (propodus), latter with five to six additional blunt teeth. Palm with simple setae of different lengths and with pappose setae. Setae in higher densities around cutting edge and at base of fingers. Whole surface of cheliped and palm pilose owing to short pappose setae.

Walking legs (P2–P5) with long, pointed, slightly curved dactyli. Dactyli of P2–P5 considerably more than half as long as propodus. Dactyli of equal length in walking legs P2–P4, slightly longer in P5: approximately as long as three-quarters of propodus. Swimming fringes of second and third walking legs present in juvenile females, reduced in adults.

Third maxilliped ( Figure 3C ). Third maxilliped with large completely fused merusischium-article. Dactylus of palp inserting underneath propodus (subterminally). Flagellum two-segmented with tuft of long simple setae originating from its tip. Third maxillipeds’ inner margins densely fringed with long simple setae. Short pappose setae distributed over whole surface of maxilliped.

Comments

Hesse (1872) was the first to describe specimens from sea squirts as a new species, namely Pinnotheres ascidicola from the northern French Atlantic coast around Brittany. Miers (1886) listed it as P. ascidiicola [sic] among a number of other Pinnotheres -species without giving any definition.

One of Hesse’s main reasons to assign these pea crabs to a separate species was their ascidian host. While he presupposed that the established species P. pisum and N. pinnotheres live exclusively in bivalves, he found his specimen in “l’ascidie phallusiennes ( Ascidia canina )” and “ Ascidia intestinalis ”, which are, according to the literature, synonyms of Phallusia mammillata (Cuvier, 1815) and Ciona intestinalis (Linnaeus, 1767) .

Further arguments, brought forward by Hesse, were the differences in size and colour, the carapace being less transparent, and his observation of P. ascidicola not being pilose, which is said to be the case in the other species, especially in N. pinnotheres . The general colour was characterized as sepia; the eyes were red. Moreover, Hesse described antennae, chelae, walking legs and third maxillipeds, without any comparison to P. pisum or N. pinnotheres . He stated for example that the first antenna was composed of three articles, the second antenna of four articles and the third maxillipeds’ flagellum of two articles, but he didn’t mention that all these characters are consistent with N. pinnotheres .

Pinnotheres marioni is mentioned for the first time in Gourret (1884) as “ Pinnotheres nov. spec. ” out of Ascidia mentula from the Gulf of Marseille in the French part of the Mediterranean Sea. Only one drawing of the telson of the zoea is shown. In 1888, Gourret gave a detailed description, naming the species Pinnotheres Marioni in honour to his Professor A.F. Marion in the article on “quelques Crustacés parasites des ascidies”. Drawings were displayed for the male, the female’s carapace as well as pleon and chelae of both sexes and zoea larvae. All features shown in these drawings are, again, absolutely consistent with our analysis and description of N. pinnotheres .

According to Gourret (1888), P. marioni differs from P. pisum and N. pinnotheres in being pilose and in the carapace not being translucent. The front of the male was described as pronounced with a median incision. He pointed out that this character clearly differs from P. pisum , but admitted that it resembles N. pinnotheres . The first antenna was said to differ from P. pisum in having three articles, which is also the case in N. pinnotheres . The characters described by Gourret were mainly compared by him with P. pisum , but not compared thoroughly with N. pinnotheres . In addition to this, Gourret was obviously not aware of Hesse’s description of P. ascidicola 15 years earlier, otherwise he should have compared his supposed new species with that one. From the original descriptions of P. ascidicola and P. marioni and the mentioned range of ascidian hosts, it becomes clear that Hesse and Gourret were talking about one and the same species.

One feature, pointed out by Hesse and Gourret as an argument for the inhabitants of sea squirts being separate species, is their degree of pilosity respectively the non-pilosity of the whole body. While P. ascidicola was said to be smooth, P. marioni was stated to be pilose. But since both authors were already misjudging the pilosity of P. pisum and N. pinnotheres – Hesse having said both species were pilose, Gourret having maintained just the opposite – we assume that they probably just did not have adequate optical methods and the sufficient degree of magnification for a proper examination of very small setae. A study of the setae types by scanning electron microscopy ( SEM) has been carried out by us for the European species, revealing that the carapace of P. pisum is smooth, while N. pinnotheres is pilose (Becker and Türkay, unpublished).

Figures

Figure 2. Male of Nepinnotheres pinnotheres. (A) dorsal view on male; (B) pleon, margin fringed with setae; (C) ventral view on left first gonopod; (D) dorsal view on left first gonopod.

Figure 3. Female Nepinnotheres pinnotheres. (A) Dorsal view on female, carapace setose; (B) left cheliped with setose surface; (C) exterior surface of left maxilliped.