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Zoology Publications from Victoria University of Wellington—Nos. 49 to 51

Congericola van Beneden, 1854 — Congericola pallidus van Beneden, 1854

Congericola van Beneden, 1854

Congericola pallidus van Beneden, 1854

Congericola pallida van Beneden, 1854, p. 583. Norman and Scott, 1906 (non vide); Scott and Scott, 1913, p. 124; Brian, 1924, p. 400; Scott, 1929, p. 100; Delamare Deboutteville and Nunes-Ruivo, 1958, p. 226; Willey, 1958, p. 370.

Cycnus pallidus (van Beneden), Richiardi, 1880, p. 150: Valle, 1884, p. 2; Scott, 1900, p. 160, Scott, 1901, p. 127; Brian, 1906, p. 76.

Yamaguti (1963, p. 159) has pointed out that Congericola is masculine.

Material

On Conger vereauxi: five females taken at Moa Point, Wellington, collected by the author, 10 December 1964; two females presumably from the Wellington area, collected by H. Manter in 1951.

Description

Female (figs. 78-88).

Overall length 3.62 mm-4.02 mm.

Cephalothorax subovate, length three-quarters width (0.54 mm-0.62mm × 0.78 mm-0.83 mm), the antennae borne laterally on a short anterior extension, one-third carapace width, the anterior margin of which is sublinear; anterior half of carapace with two irregularly subovate markings lying either side of the mid line, and joined posteriorly by a groove in the form of three sides of a rectangle, directed posteriorly. Second thoracic segment, length half width (0.27 mm-0.36 mm × 0.57 mm-0.63 mm) narrowing slightly anteriorly and posteriorly, lateral margins curved.

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Congericola pallidus van Beneden, 1854. Female—fig. 78: dorsal view; fig. 79: anterior, ventral view; fig. 80: first antenna; fig. 81: second antenna; fig. 82: mouth tube and mandibular palp; fig. 83: maxilla; fig. 84: first periopod; fig. 85: second pereiopod; fig. 86: third pereiopod; fig. 87: fourth pereiopod; fig. 88: caudal lamina.

Congericola pallidus van Beneden, 1854. Female—fig. 78: dorsal view; fig. 79: anterior, ventral view; fig. 80: first antenna; fig. 81: second antenna; fig. 82: mouth tube and mandibular palp; fig. 83: maxilla; fig. 84: first periopod; fig. 85: second pereiopod; fig. 86: third pereiopod; fig. 87: fourth pereiopod; fig. 88: caudal lamina.

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Third thoracic segment similar in shape and size to second (0.25 mm-0.38 mm × 0.57 mm-0.64 mm).

Fourth thoracic segment fused with genital segment to form a trunk, although in some specimens this trunk narrows slightly one-quarter to one-fifth of distance from anterior margin, and this slightly more swollen anterior region appears to mark the limit of the fourth segment.

Trunk including fourth thoracic segment, subrectangular, angles very broadly rounded, width two-fifths length (2.07 mm-2.58 mm × 0.95 mm-1.05 mm).

Abdomen incompletely fused with trunk, but distinguishable by sudden narrowing of the trunk posteriorly, subrectangular, length two-fifths width (0.16 mm-0.19 mm × 0.23 mm-0.48 mm), narrowing slightly posteriorly, posterior angles slightly rounded, caudal laminae carried laterally on posterior margin.

Caudal laminae subovate, anterior margin sublinear, width two-fifths length (0.14 mm-0.17 mm × 0.05 mm-0.06 mm), with one broad seta on posterior margin, one small spine just outside this seta, two small spines just inside this seta, and a further small spine on inner margin one-quarter distance from distal margin.

Egg strings 5.1 mm-9.4 mm in length, with about 130 eggs in the longest.

First antenna of nine segments, the relative lengths of the segments gievn by the following ratio—12:2:3:2:2:2:2:5:8; all segments subrectangular, the distal segment rounded distally; first segment width two-thirds length, a little narrowed distally, with five setae on outer margin; second segment length two-fifths width, with one seta on outer margin; third segment length two-thirds width, with four setae on outer margin; fourth segment length half width, with one seta on outer margin; fifth segment length half width; sixth segment length two-thirds width, with two setae on outer margin and one seta on inner margin; seventh segment as long as wide with two setae on outer margin; eighth segment width half length, with one seta on outer distal angle; ninth segment width one-quarter length, with about nine setae on distal margin.

Second antenna of two segments, placed on a stout base, first segment width half length, narrowing slightly and rounded distally; second segment basal width one-third length, narrowing gradually to a sharp point distally, the distal half strongly curved.

Mouth tube 0.17 mm in length, basal width three-quarters length, narrowing gradually to two-thirds this width distally, distal margin slightly rounded.

Mandibular palp biramous, the rami placed on a subrectangular base, outer ramus with two setae, the innermost as long as ramus, outermost one-third this length; inner ramus as long as outer, width two-thirds length, rounded distally, with two setae and a short blunt process distally.

Maxilla of two segments, these segments subequal in length, first segment width two-fifths length, narrowing to half this width distally; second segment width one-fifth length, the distal quarter a process which has its distal third bifurcated, each branch narrowing to a sharp point distally, the segment also bearing a seta on inner margin near base of process.

First pereiopod biramous, exopod of two segments, endopod of three segments, rami subequal in length, basipod of two segments, the basal segment expanded and broadly rounded laterally, the second segment narrower and shorter, with a large seta on distal margin, near inner margin of endopod; first segment of exopod subrectangular, outer margin slightly curved, width two-thirds length, with a flattened seta on outer page 27 distal angle; second exopod segment four-fifths length of first, subovate, width two-thirds length, with three flattened setae and three normal setae on distal region; first endopod segment subrectangular, outer margin curved, as wide as long, with a small seta near inner distal angle; second segment similar in shape but a little smaller, with one seta on inner distal angle and three setae near outer distal angle, this segment indistinctly separated from the next; third segment two-thirds length of second, as long as wide, subsemicircular, with two small setae on outer distal area and four normal setae on inner distal area.

Second pereiopod biramous, each ramus of three segments, basipod as in first pereiopod; first exopod segment width two-thirds length, outer margin slightly curved, with a flattened seta on outer distal angle, and a small seta on inner distal angle; second segment subrectangular, half length of first, as wide as long, with a flattened seta on outer distal angle; third segment almost as long as second, subsemicircular, as wide as long, with two flattened setae and three normal setae on distal margin; first endopod segment length four-fifths width, inner and outer margins slightly curved; second segment subrectangular, as long as first, as long as wide, with one seta near inner proximal angle, and two curved flattened setae on outer distal angle; third segment two-fifths length of second, subsemicircular, with one flattened seta and five small normal setae on distal region.

Third pereiopod biramous, exopod of two segments, endopod of three segments, basipod as in first and second pereiopods; first exopod segment slightly curved, width half length, distal margin rounded, with a flattened seta on outer distal region; second segment half length of first, basal width two-thirds length, narrowing slightly and rounded distally, a flattened seta on outer distal region, three small setae on remainder of distal region; first endopod segment subrectangular, a little longer than wide, outer distal angle swollen and rounded with setae on inner and outer distal angles; second endopod segment a little wider than long, outer margin rounded with two setae near outer distal angle; third segment two-thirds length of second, rounded distally, with four setae on distal margin.

Fourth pereiopod biramous, each ramus of one segment, the rami being broad flattened lamellae, basipod subrectangular, as long as wide, indistinctly spearated from the exopod; exopod three-quarters length of basipod, width three-quarters length, rounded distally, with five small spines on distal margin; endopod a little shorter than exopod, width half length, rounded distally, with four small spines on distal region.

Discussion

Two species of Congericola have previously been described. In C. gracilis (Milne-Edwards, 1840, p. 496, pl. 41, fig. 1), as shown in ventral view by Heller (1868, pl. 22, fig 6a), the fourth pereiopods are subequal in size to the first three, whereas in C. pallidus van Beneden (1854, p. 583, pl. opp. p. 589) the fourth pereiopods are significantly larger than the first three.

Wilson in his key to these species (1922, p. 58) also uses the width of the freely articulated segments as compared to the width of the head. Descriptions by other authors, and the discussion by Willey (1958, p. 370) make it clear that these animals have considerable contractile powers, hence body proportions are not useful in their taxonomy.

Apart from the original drawings by van Beneden, which are not particularly detailed, no full description of C. pallidus has ever been given. However, the present specimens are, in my opinion, sufficiently close to van Beneden's description and figures to allow them to be ascribed to his species.

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Nemesis robusta (van Beneden) female. 1-2 contracted females; 3-5 extended females.

Nemesis robusta (van Beneden) female. 1-2 contracted females; 3-5 extended females.

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This is the first record of this species in the Pacific and only the second outside the Northeast Atlantic, Mediterranean area.

Previous records include:

Northeast atlantic—on Conger vulgaris: Irish Sea and Llanddwyn Is., Caernarvon Bay (Scott, 1929, p. 100); Lancashire Coast (Scott and Scott, 1913, p. 124); Bay of Nigg (Scott, 1901, p. 127); Firth of Clyde (Scott, 1900, p. 160); Aberdeen (Scott and Scott, 1913, p. 124); Belgium (van Beneden, 1854, p. 583).

on Conger conger: Mauritania (Brian, 1924, p. 400).

Mediterranean—on Conger vulgaris: (Richiardi, 1880, p. 150); Banyuls-sur-Mer (Delamare Deboutteville and Nunes-Ruivo, 1958, p. 226); Liguria (Brian, 1906, p. 76); Adriatic (Valle, 1884, p. 2).

Northwest atlantic—on Conger vulgaris: Woods Hole, Mass. (Willey, 1958, p. 370).

The occurrence of this species in New Zealand waters suggests that its distribution must be much more widespread than the above list would indicate.