Peniculus minuticaudae Shiino, 1956

Maran, B. A. Venmathi, Moon, Seong Yong, Oh, Sung-Yong, Ho Young Soh, & Myoung, Jung-Goo, 2012, Redescription of two Pennellids (Copepoda, Siphonostomatoida) from Korea with a key to species of Peniculus von Nordmann, 1832, ZooKeys 243, pp. 1-14 : 4-5

Peniculus minuticaudae Shiino, 1956 Figures 23

Peniculus minuticaudae Shiino, 1956: 593; Nagasawa et al. 2011: 43; Yamaguti 1963: 1104.

Peniculus sp. Fukuda 1999: 57.

Material examined.

10 ♀♀ (NIBRIV0000245080) and 2 ♀♀ (MABIK CR00178439) from Thamnaconus modestus , Tongyeong, Gyeongsangnam-do, Korea, 20 September 2011.

Description.

Postmetamorphic adult female . Body (Figure 2A), 2.42 (2.12-2.73) mm long (n=10) comprising oval head, slender neck, large trunk and reduced abdomen. Head (cephalothorax) ovoid, longer than wide, with blunt pointed apex (Figure 2B, C). Short slender neck (Figure 2C) consisting of three somites bearing legs 1, 2 and 3. Fourth pedigerous somite incorporated into trunk. Trunk large, cylindrical, longer than wide, bearing leg 4 proximally (Figure 2C). Abdomen slightly triangular-shaped (Figure 2D, E) long with subterminal caudal rami on ventral surface and projecting posterior tip with anal indentation. Egg sacs long and uniseriate with 33-40 eggs (Figure 2F). Caudal rami (Figure 2G) bearing 2 long, 3 medium sized subequal, 1 small setae. Antennule not observed. Antenna (Figure 2H) 2-segmented, chelate; proximal segment consisting of 2 pointed projections overlapping each other; terminal segment claw-like, acutely pointed with minute seta at base.

Mandible (Figure 3A) broad with 10 teeth terminally. Maxillule (Figure 3B) with 2 lobes having one and two long setae. Maxilla (Figure 3C) 2-segmented; proximal segment broad with spiniform small process, 2 rows of setules distally; distal segment blunt and curved with transverse striations and rows of spinules. Maxilliped absent. Legs 1 to 4 (Figure 3 D–G) all represented by broad plate-like structures derived from the protopodal segments, without rami or seta. Leg 5 absent.

Variability.

Some females showed variation on posterior end of trunk and abdomen (Figure 3 H–J).

Attachment site.

All fins of host fish.

Remarks.

Careful comparison between our material and the original description of Peniculus minuticaudae provided by Shiino (1956) revealed some differences: (1) the abdomen was described as trapezoid and rhomboid; (2) the striation and fine setulose ornamentation of the maxilla was not shown. The mandible was not described. Our redescription revealed that the abdomen of Peniculus minuticaudae is triangular and protrudes, however, the two closely related congeners Peniculus ostraciontis and Peniculus truncatus both have a rudimentary abdomen. We also noted some variation in the posterior end of trunk and abdomen (Figure 3 H–J). In the maxilla, fine striations and rows of setulose were found on the distal segment. In addition, the trunk is long and narrow in Peniculus minuticaudae and there is no major gap between cephalothorax and trunk so it has a short neck, where legs 1 to 3 are located (Figure 2C). Leg 4 (Figure 2C) is embedded on the anterior part of the trunk. In comparison, the closely related congener Peniculus ostraciontis has a stout trunk and short neck ( Yamaguti 1939) while Peniculus truncatus has a long trunk and neck, and leg 1 has minute setal structure which are not present in Peniculus minuticaudae and Peniculus ostraciontis .