Echinolaophonte armiger (Gurney, 1927)

Fuentes-Reines, Juan Manuel & Suarez-Morales, Eduardo, 2017, A new species of Echinolaophonte and record of E. armiger (Gurney, 1927) (Crustacea, Copepoda, Harpacticoida, Laophontidae) from the Caribbean with a key to species, ZooKeys 722, pp. 19-36 : 26-28

Echinolaophonte armiger (Gurney, 1927) Figs 6 C–D, 7

Syn. Laophonte armiger Gurney, 1927: 554-556, fig. 159; Willey 1930: 108-109, figs 65-67; Carvalho 1952: 159-160, Pl. II, figs 68-71. Onychocamptus armiger Lang, 1948: 1423-1424, Abb. 571(12), 580.

Material examined.

One dissected adult female (CBUMAG:MEI:0003), two adult males and four adult females, ethanol-preserved, vial (CBUMAG:MEI:0002; CBUMAG:MEI:0001); Colombia, Magdalena, Rodadero Bay, 11°14'N, 74°12'W, August, 2016; coll. J.M. Fuentes-Reinés. One male, one female prepared for SEM analysis.

Description.

Female. Habitus as in Figure 7A. Body cylindrical in dorsal view, prosome gradually tapering anteriorly. Total body length measured from anterior margin of rostrum to posterior margin of caudal rami ranging from 616 to 644 μm (average = 624.4 μm, n = 5). Rostrum conical in lateral view, trapezoid with flat anterior margin in dorsal view (Fig. 7B). Strong, dorsal spinous process present at median posterior margin of cephalosome reaching midlength of second pedigerous somite; process smooth in lateral view (arrow in Fig. 7A, C). Cephalosome with lateral posterior corners produced into triangular expansions (arrows in Fig. 7G) with weak cuticular incisions.

Antennule (Fig. 7D) 6-segmented, with long aesthetasc on fourth segment. Antenna (Fig. 7E, F) three-segmented, comprising coxa, allobasis, one-segmented endopod and one-segmented exopod, antennal exopod one-segmented with four well developed, pinnate setae (two lateral, two apical).

Mandible, maxillule, maxilla, and maxilliped (Fig. 6C) as in syntype specimens of E. armiger ( Lee et al., 2006), except for seta on maxillary coxa (arrow in Fig. 7H).

P1 (Fig. 7I) with ENP and EXP two-segmented, ENP1 length/width ratio = 5.6, ENP2 ratio = 2.8, with denticulate claw and small, naked seta at base. EXP short. EXP1 with unipinnate spine. EXP2 with three unipinnate spines and two geniculate setae. P2-P4 as described by Lee et al. (2006).

P5 (Fig. 7J) with EXP and baseoendopod separate; each covered with spinules. Baseoendopod with short setophore bearing basal seta. Endopodal lobe armed with four setae, exopodal lobe with three. P6 represented by one inner small and one outer longer seta. Caudal rami length/width ratio = 1.4.

Male. Habitus resembling that of female (Fig. 7K). Total body length ranging from 532 to 588 μm (average = 560 μm, n = 3).Cephalosome with strong dorsal spiniform medial process as in female (arrowed in Fig. 6K). Antennule (Fig. 7L) subchirocer, eight-segmented, with geniculation between segments 5 and 6. First segment with row of spinules, second segment with small subdistal knob. Segment 5 swollen, segment 6 with spiniform processes. Maxilliped with relatively narrower basis and longer terminal claw than in female (Fig. 6D).

P1 (Fig. 7M) and P2 as in female; P3-P4 as in female, except for outer and distal spines of exopod which are slightly thicker than in female. P5 (Fig. 7N) fused medially, defined at base. Baseoendopod with short setophore bearing long outer basal seta, endopodal lobe obsolete. Exopod narrow, armed with three pinnate setae and spinules on anterior surface. P6 (Fig. 7O) represented by subquadrate plate armed with bipinnate inner and naked outer seta. Caudal rami length/width ratio = 1.4.

Variability.

One male was observed to have three setal elements on the antennal exopod instead of the usual pattern of four.

Remarks.

The present record, from the Caribbean coast of Colombia, is the fifth of E. armiger sensu Gurney, 1927 worldwide. In the surveyed area this species coexists with the closely related E. villabonae , which is locally more abundant. Lee et al. (2006) redescribed E. armiger from syntypic specimens from the Suez Canal and complemented their report with specimens from the Gulf of Mexico (Texan Coast, USA); the species is characterized by: 1) the smooth apical margin of the rostrum, 2) the simple dorsal spinous process on the cephalosome, 3) the armature formula of the swimming legs, 4) the short ENP2 of P2-P4, 5) the unmodified P3 endopod in male, 6) the slightly modified exopods of P3 and P4 in male, 7) the short setophore of the P5 outer basal seta, 8) short caudal ramus (only 1.4 times longer than wide), 9) the shape of dorsal spiny processes in the prosome and urosome and 10) the shape of pseudoperculum. Most of these distinctive traits were observed in the Colombian specimens. However, subtle differences were detected in our specimens from Colombia, thus allowing an expansion of the morphological range of this species: 1) a maxillary coxal seta is present in the Colombian specimens (Fig. 7H) whereas it is absent in the Texan material ( Lee et al. 2006: fig. 2F), 2) the P1ENP1 length/width ratio. It is 5.6 in the Colombian specimen (Fig. 7I) whereas in the Texas specimens the figure is slightly higher: 5.8 ( Lee et al. 2006: fig. 3A).

Distribution.

Suez Canal, Egypt (type locality), the Texan coast (USA) ( Lee et al. 2006), Brazil ( Carvalho 1952), northern Colombia (present data), and possibly Bermuda ( Willey 1930).