Harpinia truncata Sars

Harpinia truncata Sars

(figs. 3–4)

Harpinia truncata Sars, 1891:157, pl. 55, fig. 1. — Stebbing, 1906:144. — Stephensen, 1938:156. — Barnard, 1960:357. — Watling, 1981:209, fig. 5 J–L.

Material examined. — Trondhjemsfjorden, Norway, 1 female, ZMO F13092. Risør, Norway, many female specimens, ZMO F13235. Location unrecorded, 3 males, ZMO F13236. Location unrecorded, 2 females, ZMO F13151.

Distribution. — Norway, Iceland, Western Atlantic to 38° N.

Diagnosis. — Female. 6.0 mm. Coxal plates 1–3 without spines on posterodistal corner. Antenna 1 flagelum of seven articles, accessory flagellum with six. Antenna 2 flagellum with seven articles. Gnathopod 2 propodus much larger than gnathopod 1. Pereopod 7 basis broad, posterior margin somewhat truncated entire posterior margin with at least six indistinct spines associated with small setae, anterior margin with three long plumose setae and two short simple setae above insertion of ischium; ischium with 3 plumose setae and two simple setae above insertion of merus; dactylus as long as propodus. Epimeron 2 with 8 distal setae; epimeron 3 posterodistal corner with excavated notch and a small spine with associated seta, with 3 long setae on lateral face. Uropod 3 outer ramus article 2 less than 1/3 as long as article 1, with long seta (as long as entire ramus), article 1 with three to five lateral setae; inner ramus not reaching to article 2 of outer ramus, with apical seta (reaching just past article 2 of outer ramus).

Description. — Male. (Sexually dimorphic characters) 5.0–6.0 mm. Head without spine on dorsolateral margins. Antenna 1 with tufts of long, fine setae on peduncular articles 1­3 and flagellar article 1, article 1 of flagellum elongate; flagellum with four to five articles, accessory flagellum with five articles. Antenna 2 with tufts of fine setae on peduncular articles 3 and 4; flagellum with six articles. Coxa 1–3 without spines on posterodistal corner. Gnathopods 1 and 2 with an elongate, narrow propodus, with robust seta defining palm. Pereopod 6 missing in specimen. Pereopod 7 basis extending to distal margin of ischium, without distinct spines or setae on posterior margin; all articles lacking long plumose setae seen in female. Urosomites narrow, urosomal segment 3 with dorsal elevation anterior to insertion of telson. Epimeron 2 without distal setae; epimeron 3 posterodistal corner with excavated notch and a small spine, with an associated small seta, without long setae on lateral face. Uropod 3 rami elongate, outer ramus article 2 about 1/3 length of article 1, without apical seta, inner ramus as long as outer ramus, without apical seta.

Remarks. — The female of Harpinia truncata was well described by Sars (1891) from specimens from Trondhjemsfjord, Norway and the coast of Bohuslän, Sweden, therefore a diagnosis is given for comparison with the male.

The males examined here were found in a large sample of Harpinia specimens containing females of H. truncata and H. pectinata. The males of H. pectinata have been described (King et al., 2004) leading to the conclusion that the males were those of H. truncata. In addition, previous studies by this author suggest that the morphology of Harpinia males somewhat reflects that of the female, for instance, if the female possesses a distinct posterodistal spine on epimeron 3, then the male will have a smaller version; if the female has a small spine or notch, the male will also have a notch. Also, it has been noted that in the males of species that possess a posterodistal spine on epimeron 3, the gnathopods tend to be elongate and do not have a robust seta defining the palm. The male specimens described here as H. truncata match the female H. truncata in all the characters described above. Unfortunately, the locality of the specimens was not recorded on the label but they are from the Sars collection in the ZMO, Norway and are assumed to be from the Norwegian area.

The male of Harpinia truncata is most similar to the males of H. laevis and H. crenulata (See King et al., 2004) in that the posterodistal corner of epimeron 3 is not produced into a distinct spine but rather an excavate notch with associated small seta and that there is a robust seta on the propodus of gnathopod 1. The male of H. truncata differs from the male of H. laevis by the possession of a smooth posterior margin on the basis of pereopod 7, more triangular shaped propodus of gnathopod 1 and the thick tuft of setae on the antennal peduncular articles. The male H. truncata differs from the male of H. crenulata by the possession of a broad basis on pereopod 7 with a smoother distal margin and by the morphology of uropod 3: in males of H. truncata the rami are sub equal, while in males of H. crenulata the inner ramus is half the length of the outer ramus.