Speleonectes emersoni, Lorentzen, Dörte, Koenemann, Stefan & Iliffe, Thomas M., 2007

Speleonectes emersoni new species

( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Type locality. Cueva Los Jardines Orientales, south coast near Santo Domingo, Dominican Republic.

Material examined. Holotype (deposited at Biozentrum Grindel und Zoologisches Museum, Hamburg; catalogue number K - 41270) ( 12.5 mm, 21 trunk segments), five paratypes ( 9.5 mm, 19 trunk segments; 10.5 mm, 20 trunk segments; 11 mm, 20 trunk segments; 11 mm, 20 trunk segments; 11.5 mm, 20 trunk segments; all in research collection of SK) from Cueva Los Jardines Orientales. One paratype ( 10 mm, 20 trunk segments) from Cueva Taina. Specimens were collected on May 1, 2005 (Cueva Taina) and May 5, 2005 (Cueva Los Jardines Orientales) at or below the halocline in 15–37 m depth by Thomas Iliffe. The holotype and one paratype (whole specimens) are preserved in alcohol; two paratypes were dissected and preserved in glycerine; three paratypes were used for molecular analyses.

Etymology. The epithet emersoni is in honor of the biologist Michael James Emerson ( 8 May 1954 – 22 March 1990). Michael worked as a research assistant on the “Remipede Project” at the San Diego Natural History Museum from 1982 to 1990. His experience as a skillful scientific illustrator and attentive observer resulted in several publications that set benchmarks in the systematics of Remipedia.

Diagnosis. A small-sized, slender species, up to 12.5 mm, adult specimens composed of 19–21 segments; pleural tergites weakly developed, with rounded lateral margins in anterior part of trunk, becoming slightly pointed in posterior trunk; dorsal ramus of antennule 11-segmented, ventral ramus with 6 segments; arcshaped, horseshoe-like claw of maxilla and maxilliped composed of 7–10 denticles; anal segment longer than wide; caudal rami approximately as long as anal segment.

Description. Based on holotype and paratypes. Body slender with a maximum length of 12.5 mm and 21 trunk segments ( Fig. 1 View FIGURE 1 ). Pleural tergites narrow, with rounded distolateral corners on trunk segments 1–7 ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 A), becoming slightly acuminate in posterior part of trunk, tergite on first trunk segment reduced. Sternal bars sublinear and isomorphic. Male gonopores on trunk limb 14 cylindrical, with rounded pointed lobes ( Fig. 2 View FIGURE 2 B). Head shield subrectangular, tapering at anterior end, approximately as long as trunk segments 1–3 ( Fig. 2 View FIGURE 2 A). Frontal filaments with relatively short distomedial processes, extending beyond tip of main filament ( Fig. 3 View FIGURE 3 A).

Antennule ( Fig. 3 View FIGURE 3 B): Peduncle with small bulbus bearing relatively few aesthetascs. Dorsal flagellum 11- segmented, almost twice as long as head shield, reaching 9% of length of body. Ventral flagellum with 6 segments, nearly half as long as dorsal flagellum, as long as head shield.

Antenna ( Fig. 3 View FIGURE 3 C): Proximal segment of protopod with 2 marginal setae; distal segment with 4 marginal setae. Exopod longer and wider than adjacent distal segment of protopod, bearing 18–20 long setae. Endopod bent in a semicircular arc; first two proximal segments with 5–6 and 4–5 setae, respectively; distal segment with about 15 setae arranged in two rows composed of 9 and 5–6 setae. All setae faintly plumose.

Mandible ( Fig. 3 View FIGURE 3 D, E): Right incisor process and lacinia mobilis with three large denticles. Left incisor process with four large denticles; left lacinia mobilis crescent-shaped, apical margin serrate. Molar process prominent.

Maxillule ( Fig. 4 View FIGURE 4 A, D, E): Segment 1 with slender endite, distal margin terminating in 4 long stout setae (one of which prominent) and about 3 simple setae. Endite of second segment long and broad, with 2 setae at inner proximal margin; 6 stout, relatively large setae (all of which simple, except one setulose seta ( Fig. 4 View FIGURE 4 E)) and 5–6 fine setae arranged in a second row on distomedial and -lateral margins and two long setae on distolateral margin. Segment 3 short; endite tapering, slightly rounded, bearing 2 long, robust setulose setae and 1 simple seta. Segment 4 (lacertus) subtriangular, with obliquely expanded medial margin; proximal corner bearing 2 long, robust setae ( Fig. 4 View FIGURE 4 D) and 4–5 simple setae. Segment 5 as long as lacertus, but narrower, with a cluster of distomedial setae. Sixth segment equipped with separate clusters of long and shorter setae on distal margins. Claw slender, well-developed ( Fig. 4 View FIGURE 4 A).

Maxilla ( Fig. 4 View FIGURE 4 B): First endite of segment 1 bearing 2 short apical stout setae. Endites 2 and 3 of first segment each with 1 prominent apical stout seta accompanied by 2–4 short setae on subapical margins. Endite of segment 2 equipped with a single, short stout seta and a few long setae. Segment 3 (lacertus) slightly pearshaped, medial margin bearing 4–6 long and short setae. Segment 4 shorter than segment 3; distomedial margin rounded, with a cluster of 2–3 setae. Segment 5 shorter than segment 4, subquadrangular; distomedial corner with a cluster of 5 long and shorter setae. Segment 6 nearly as long as segment 5, with a row of about 7 setae along distomedial margin and a row of about 6 setae on distoposterior margin. Arc-shaped, horseshoetype claw serrated, composed of 7–10 small denticles flanked by 2 stronger, separate denticles. All setae simple.

Maxilliped ( Fig. 4 View FIGURE 4 C, F): Distinctly longer than maxillule, slender. Segments 1 and 2 bearing a few long medial setae. Segment 3 rather long, with 4 long setae. Segments 4–6 gradually decreasing in length; fourth segment with a row of 4 medial setae. Segment 5 with distomedial margin slightly expanded bearing 2 long setae. Segment 6 bearing 2 setae on distomedial margin. Segment 7 subquadrangular, with a row of about 6 long and shorter setae at distomedial margin. Eighth segment approximately as long as segment 7, equipped with a row of about 13 setae at distomedial margin and 7 short setae on distolateral margin. Claw subequal to that of maxilla ( Fig. 4 View FIGURE 4 F). All setae simple.

Trunk appendages ( Fig. 2 View FIGURE 2 B, D): Segment 1 of exopod equipped with 3–6 long setae and up to 2 serrate stout setae on distolateral corner. Segment 2 with setae on lateral and medial margins, and 3–4 serrate stout setae on distolateral corner. Segment 3 ovate, bearing 14–17 long marginal setae. Endopod slightly shorter and narrower than exopod; distribution of long plumose setae like those on exopod, with the following exceptions: basal segment naked; segment 3 with 2 serrate stout setae on distolateral corner and 1 serrate stout setae on distomedial corner; segment 4 with 10–12 setae ( Fig. 2 View FIGURE 2 B). All setae plumose. Anal segment ( Fig. 2 View FIGURE 2 C): 1.2 times longer than wide; caudal rami about 1.1 times longer than anal segment, bearing a few very fine setae along margins and about 3 fine, apical setae.