Some New Zealand Parasitic Copepoda of the Family Anthosomidae
Lernanthropus Blainville, 1822
Lernanthropus Blainville, 1822
Anthosomidae. Female: Head fused with first thoracic segment, cephalothorax margins turned down ventrally; second and third thoracic segments fused; fourth thoracic segment fused to second and third, rarely free, covered by a dorsal plate which extends posteriorly to cover the genital segment, and sometimes the abdomen and caudal rami, in dorsal view; genital segment small, rounded; abdomen one-or two-segmented; caudal rami present, flattened or subcircular in cross section, usually tapering posteriorly; eggs uniseriate, flattened; egg strings usually long, trailing posteriorly from genital segment; first antenna with segments more or less fused, sometimes distinct; second antenna subchelate; mandibular palp present; maxilla two-segmented; maxilliped subchelate; first four pereiopods biramous; rami of first and second pairs rudimentary, one-segmented; those of third pair lamellar, fused, projecting at right angles or diagonally from ventral surface! rami of fourth pereiopods usually separate, lamellar, extending posteriorly; fifth pereiopods uniramous, rudimentary or lacking. Male as for Paralernanthropus. Parasitic on marine teleosts.
Type species: L. musca Blainville, 1822.
Lernanthropus microlamini n.sp.
From Seriolella brama, one female, collected by H. Manter in 1951, presumably in the region of Wellington.
Female (figs. 25 - 36).
Overall length 9.92 mm.
Cephalothorax subrectangular, angles rounded, little longer than wide (2.67 mm × 2.52 mm), anterior three-quarters of lateral margins parallel, cephalothorax narrowing slightly posteriorly; antennae borne on anterolateral bulges of a frontal area which is one-third cephalothorax width and one-seventh cephalothorax length, marked laterally by grooves, its sublinear anterior margin forming a dip in the anterior margin of cephalothorax, remainder of anterior margin of cephalothorax an entire curve on either side of frontal region.
Second and third thoracic segments fused, as wide as long (3.20 mm × 3.35 mm), widest posteriorly, narrowing anteriorly to half this width, projections on the posterior two-fifths of the lateral margin extend over part of surface of third pereiopod, and increase this width by two-sevenths.
Fourth thoracic segment, including plate, subrectangular, angles rounded, four-fifths as wide as long (4.27 mm × 3.39 mm) narrowing to three-quarters this width posteriorly; actual segment very short.
Genital segment very small, subovate, partly hidden in ventral view by third pereiopods, which were not dissected off to reveal this segment.
Abdomen subrectangular, posterior angles rounded, width half length (0.65 mm × 0.49 mm), narrowing slightly posteriorly.
Caudal laminae, width two-fifths length (0.45 mm - 0.19 mm), widest at base, narrowing slightly distally, distal margin rounded, three smal lspines borne distally.
Egg strings 13.00 mm in length, eggs uniserial, egg strings trailing behind body.
First antenna of seven segments, basal segment half length, second and third segments subequal in length, together half basal segment length, remaining segments progressively shorter; basal segment, basal width two-thirds length, narrowing to half this width distally, with two setae on outer margin and one on inner margin; second segment as wide as long, subovate; third segment as wide at the base as second, narrowing to two-thirds this width distally, with one seta on outer margin; fourth segment subovate, four-fifths as wide as long, with one seta on outer margin; fifth segment two-thirds as wide as long, with two setae near distal margin; terminal segment, width two-thirds length, rounded distally, with five setae on inner distal region, and three small spines near outer distal region.
Second antenna of two segments, subchelate; first segment, basal width two-thirds length, narrowing to nearly half this width distally, curving slightly; second segment three-quarters length of first, basal width half length, narrowing suddenly to half this width one-third distance from base, then narrowing slowly to a sharp point distally, distal two-thirds sharply curved.
Mouth tube small (0.4 mm in length), and sharply pointed distally.
Mandibular palp biramous, rami borne on subrectangular base, outer ramus, width half length, rounded distally; inner ramus as wide as outer, two-thirds its length, both rami with one large and two small spines distally.
Maxilla of two segments, segments subequal in length, first segment subrectangular, half as wide as long; second segment basal width one-quarter length, narrowing gradually to a blunt tip, with a spine on inner margin two-sevenths distance from tip, two spines one-seventh distance from tip, and two rows each of about seven very small spines between these two and the tip.page 10
Lernanthropus microlamini n.sp. female: fig. 25: dorsal view; fig. 26: lateral view; fig. 27: ventral view; fig. 28: spine from between first and second antennae; fig. 29: second antenna; fig. 30: mandibular palp; fig. 31: maxilla; fig. 32: tip of maxilla; fig. 33: maxilliped; fig. 34: first pereiopod; fig. 35: second pereiopod; fig. 36: caudal lamina.
Maxilliped of two segments, subchelate; basal segment swollen, basal width half length, narrowing to two-thirds this width distally, outer margin strongly curved, inner margin with two small spines; second segment three-quarters length of first, basal width two-fifths length, narrowing to a point distally, sharply curved, particularly over distal half.
First pereiopod biramous, each ramus of one segment; basipod swollen, subsemicircular, half as long as wide, with a spine near base of endopod; rami subequal in length, a little shorter than basipod; exopod, width three-quarters length, rounded distally, with four blunt flattened spines on distal margin; endopod subtriangular, as wide as long, with a seta subequal in length to segment on distal apex.
Second pereiopod biramous, each ramus of one segment; basipod swollen, almost three times length of basipod of first pereiopod, similar in shape except that it swells more strongly laterally than does basipod of first pereiopod; exopod one-seventh basipod length, subsemicircular, proximal margin straight, as wide as long, with five small flattened blunt spines on distal and inner margins; endopod three-quarters length of exopod, width two-thirds length, rounded distally, with no setae.
Third pereiopod laminate, rami fused or lost, laminae a little wider than plate on fourth thoracic segment, lying transversely across body, overlapping slightly in the midline, and extending posterolaterally from the body for almost one-third their length, slightly curved, standing out at right angles from the body for a distance equal to one-fifth body length.
Fourth pereiopod biramous, rami flattened lamellae separated almost to their base, exopod, width one-quarter length, narrowing gradually to one-quarter this width distally and then rounded, extending posterolaterally beyond plate of fourth segment for more than half its length; endopod five-sevenths length of exopod, two-fifths as wide as long, inner margin sublinear, outer margin curved over distal three-fifths of its length to reduce width to one-eighth basal width, lamella then rounded distally.
L. microlamini seems to be most closely related to a group of species or subspecies recorded from many parts of the world on Caranx spp. Initially these were described as L. giganteus by Krøyer (1863, p.280, pl. 8, fig. 1) from Brazil, then Wilson recorded specimens from the West Indies (1913, p.227, pl. 33, fig. 148-150, pl. 35) under the same name, although Wilson's figures differ from those by Krøyer in the length of the plate of the thoracic segment (40% of total length in Krøyer's figure, 30% in Wilson's), as well as in the shape of this plate; Kirtisinghe (1956, p. 18, fig. 11) recorded specimens from Colombo under the name L. trifoliatus Bassett-Smith but later (1964, p.98, figs. 132-137) gave further records from the Gulf of Mannar area, now placing these and his previous records as L. giganteus; meanwhile Pillai (1964, p.48, fig. 9) recorded specimens from the same host genus from nearby Trivandrum as L. carangis Pillai (nec. L. carangis Hesse, 1878 which page 12was removed from the genus Lernanthropus by Wilson, 1922, p.46); these Indian Ocean specimens differ from those of Wilson and Krøyer in having a broadly laminate fifth pereiopod while the latter show their specimens as having filiform fifth pereiopods.
The present material can readily be distinguished by the third pereiopods which extend little beyond the plate of the fourth thoracic segment, while in the above records these appendages project beyond the plate for one-third its length, and also by the lack of fifth pereiopods which are well developed in the above records.
The present species is also very similar to L. trifoliatus Bassett-Smith (1898, p.12, pl. 7, fig. 1) but differs in having the plate of the fourth thoracic segment narrowed posteriorly while in L. trifoliatus it becomes wider and then broadly rounded posteriorly, and again in the lack of the fifth pereiopods which are particularly well developed in L. trifoliatus.
It seems possible that the present species and L. trifoliatus are closely related to the specimens recorded from Caranx spp. but, until such time as larger collections from a variety of geographical localities makes revision of this group possible, there is no way of deciding the extent of this relationship.