Lernanthropus pemphericola, Boxshall & Bernot & Barton & Diggles & Q-Y & Atkinson-Coyle & Hutson, 2020

Boxshall, Geoff A., Bernot, James P., Barton, Diane P., Diggles, Ben K., Q-Y, Russell, Atkinson-Coyle, Toby & Hutson, Kate S., 2020, Parasitic copepods of the family Lernanthropidae Kabata, 1979 (Copepoda: Siphonostomatoida) from Australian fishes, with descriptions of seven new species, Zootaxa 4736 (1), pp. 1-103 : 67-72

publication ID	https://doi.org/ 10.11646/zootaxa.4736.1.1
publication LSID	lsid:zoobank.org:pub:970D7D36-6D8C-4463-B9EA-D3B8E191BE72
DOI	https://doi.org/10.5281/zenodo.3671065
persistent identifier	https://treatment.plazi.org/id/554BDB52-7323-FF88-5FC9-F9A72BF0FAEC
treatment provided by	Plazi
scientific name	Lernanthropus pemphericola
status	sp. nov.

Treatment

Lernanthropus pemphericola sp. nov.

( Figs. 35–37 View FIGURE 35 View FIGURE 36 View FIGURE 37 )

Type Material: Holotype ♀, allotype ♂, 27 paratype ♀♀, 14 paratype ♂♂ from Pempheris compressa (White, 1790) , Coffs Harbour , New South Wales; 15 May 1981; collected by M. La Spina: AM Reg. Nos. P. 103903 (Holotype ♀), P.103904 (allotype ♂), P.103905 (10 paratype ♀♀ and 5 paratype ♂♂); 10 paratype ♀♀ and 5 paratype ♂♂, QM Reg. No. W29497; 6 paratype ♀♀ and 4 paratype ♂♂ NHMUK 2018.281 View Materials – 290 View Materials .

Etymology: the name of the new species combines the generic name of the host with –icola, meaning inhabitant.

Description: Female body comprising cephalothorax, trunk and urosome ( Fig. 35A View FIGURE 35 ): body length ranging from 1.47 to 1.69 mm, with a mean of 1.59 mm (based on 10 specimens). Cephalothorax subcircular, about 1.2 times wider than long; frontal margin with convex protruding central part; lateral margins evenly convex, expanded into ventrolaterally directed folds on either side of cephalothorax; posterior margin convex. Trunk broad: anterior part (second and third pedigerous somites) wider than long, expanding posteriorly towards level of origin of third legs; posterior part (fourth pedigerous somite) with short dorsal trunk plate with rounded posterior margin ( Fig. 35A View FIGURE 35 ). Dorsal trunk plate wider than long, covering anterior part of urosome but with part of genital complex, anal somite and caudal rami all visible in dorsal view. Egg sacs linear ( Fig. 35A View FIGURE 35 ). Abdomen small, not clearly differentiated from genital complex ( Fig. 35B View FIGURE 35 ), bearing paired, elongate caudal rami. Each caudal ramus about 3.7 times longer than wide; armed with 2 long plumose setae proximally, 1 short outer seta located at about 75% of ramus length, and 2 spine-like setal elements at apex ( Fig. 35B View FIGURE 35 ).

Antennule ( Fig. 35C View FIGURE 35 ) indistinctly segmented, proximal part with irregular cuticular thickening and armed with total of 7 setae; defined apical segment with 11 + 2 aesthetascs. Parabasal flagellum absent in female. Antenna ( Fig. 35D View FIGURE 35 ) comprising robust corpus, bearing 2 small processes proximally on medial surface, and distal subchela armed with 2 small processes proximally and small seta on concave margin. Mandible stylet-like, armed with 8 marginal teeth distally ( Fig. 35E View FIGURE 35 ). Maxillule ( Fig. 35F View FIGURE 35 ) bilobate, smaller inner lobe tipped with 1 spiniform element; larger outer lobe tipped with 3 unequal setal elements. Maxilla ( Fig. 35G View FIGURE 35 ) 2-segmented: comprising proximal syncoxa (lacertus) and distal basis (brachium); basis with 1 subapical seta plus triangular process distally; terminal claw ornamented with sharp denticles along margins and fine spinules on inner surface. Maxilliped ( Fig. 35H View FIGURE 35 ) 2-segmented comprising massive corpus with papilliform element on medial surface opposing tip of claw, and distal subchela comprising compound endopodal segment and strongly curved terminal claw, armed with seta and minute process near concave margin.

Leg 1 biramous ( Fig. 36A View FIGURE 36 ); protopod well defined, intercoxal sclerite absent; basis armed with outer seta and short inner spine; exopod 1-segmented, armed with 5 robust terminal spines; endopod 1-segmented, armed with vestigial seta on apex. Leg 2 ( Fig. 36B View FIGURE 36 ) mounted on inflated prominence derived from incorporated protopod, armed with outer seta located on small prominence, and ornamented with 2 setules medially: both rami 1-segmented; exopod armed with 4 small terminal spines; endopod armed with curved apical element. Leg 3 biramous: exopod represented by flattened, horizontally-orientated lobe, visible in dorsal view; endopod represented by slightly larger obliquely-orientated lobe, extending back to about level of origin of fourth leg lobes; endopodal lobes of leg pair separate along midline ( Fig. 36C View FIGURE 36 ); outer basal seta not seen. Leg 4 ( Fig. 35A View FIGURE 35 ) biramous with rami forming elongate processes, armed with dorsal seta at base: outer (exopodal) lobe elongate, inner (endopodal) lobe slightly shorter than exopodal lobe. Leg 5 represented by small lobe bearing single plumose seta on apex ( Fig. 35I View FIGURE 35 ).

Male. Body smaller than female; body length ranging from 0.92 to 1.07 mm, with a mean of 0.98 mm (based on 10 specimens). Cephalothorax large, comprising about 46% of total body length: broadest at middle, with strongly convex lateral margins ( Fig. 36D View FIGURE 36 ); frontal area carrying antennules and antennae, narrow and defined by marked lateral indentations. Trunk comprising second to fourth pedigerous somites fused to urosome. Urosome comprising fifth pedigerous somite, genital somite and abdomen, all fused. Genital somite with linear, tapering lateral margins, more than twice width of abdomen; abdomen wider than long bearing paired caudal rami armed as in female.

Antennule indistinctly segmented ( Fig. 37A View FIGURE 37 ), proximal part armed with total of 8 setal elements; apical segment with 11 + 2 aesthetascs. Parabasal flagellum straight, with slightly swollen base, located close to base of antennule and reaching 36% along limb ( Fig. 37A View FIGURE 37 ). Antenna ( Fig. 37B View FIGURE 37 ) comprising massive corpus and distal subchela consisting of endopod plus terminal claw: corpus armed with papilliform process medially and ornamented with spinules; subchela armed with stout inner process plus; small process in articulation between corpus and subchela. Postantennal processes ( Fig. 36 View FIGURE 36 , pap) rounded located anterior to short oral cone ( Fig. 36E View FIGURE 36 , oc). Mandible similar to that of female. Maxillule with longest seta on apex of outer lobe more than twice length of shorter elements ( Fig. 36E View FIGURE 36 ). Maxilla as in female but with additional large spinules in distal part of basis and on claw ( Fig. 37C View FIGURE 37 ). Maxilliped with same segmentation as female; corpus ornamented with spinules along myxal margin, subchela with strong pointed process near concave margin ( Fig. 37D View FIGURE 37 ).

Leg 1 with well defined protopod and members of leg pair joined by intercoxal sclerite: biramous ( Fig. 37E View FIGURE 37 ) with outer seta and strong inner spine on basis; basis ornamented with spinules around origin of inner spine: exopod 1-segmented, armed with 4 terminal spines and ornamented with scattered spinules distally; endopod 1-segmented, with small elements and scattered spinules apically. Leg 2 ( Fig. 37F View FIGURE 37 ) without intercoxal sclerite; protopod defined from somite proximally and armed with outer seta; both rami 1-segmented; exopod broadening distally, armed with distal spines of varying sizes and with ornamentation of spinules laterally; endopod tapering distally, surface ornamented with scattered spinules, armed with small naked seta apically. Leg 3 ( Fig. 36D View FIGURE 36 ) uniramous, forming long cylindrical process directed laterally from trunk, armed with outer protopodal seta proximally on dorsal surface. Leg 4 ( Fig. 36D View FIGURE 36 ) uniramous, forming long cylindrical process directed posterolaterally, with outer protopodal seta proximally on dorsal surface; leg 4 lobe about 1.8 times longer than leg 3.

Distribution: This new species is known only from the type locality, Coffs Harbour, New South Wales.

Remarks: This small species is the first lernanthropid to be recorded from any member of the family Pempheridae . It is similar to L. atrox in its broad cephalothorax and narrow dorsal trunk plate allowing the dorsal surface of the posteriorly-directed leg 3 to be visible in dorsal aspect. These species differ, however, in the extent of the dorsal trunk plate which conceals the urosome including the tips of the caudal rami in L. atrox , but which reveals the posterior part of the genital complex, the abdomen and the entire caudal rami in the new species. In addition, the lobes of leg 4 are short (less than the length of the trunk) in L. atrox but elongate (almost as long as entire body) in L. pemphericola sp. nov. The males differ markedly in leg structure: legs 3 and 4 are biramous in L. atrox (see Shiino, 1955: Fig. 3C View FIGURE 3 ) but both are uniramous in the new species.

The other known Australian species with a short and broad anterior trunk and narrow dorsal trunk plate is L. breviculus , but in this species the dorsal trunk plate covers the entire urosome and caudal rami, and only the lateral margin of leg 3 is visible dorsally. In contrast, in the new species almost all of the urosome protrudes beyond the posterior margin of the dorsal trunk plate and the entire exopodal lobe of leg 3 is visible in dorsal view. In addition, the members of leg 3 pair are fused along the midline in L. breviculus , but separate in L. pemphericola sp. nov. The new species can also be distinguished from L. callionymicola by the same feature, namely that in L. callionymicola only the tips of the caudal rami are visible protruding beyond the posterior margin of the dorsal trunk plate (El- Rashidy & Boxshall, 2012) compared to almost the entire urosome in the new species.

The male of the new species has uniramous legs 3 and 4 and this is a relatively unusual condition. Although males are as yet unknown in many species, where males have been described they typically have the fourth legs (and often the third legs) biramous. So the possession of uniramous legs 3 and 4 is not common in males but it is shared with a number of other Indo-Pacific species including L. breviculus , L. callionymicola , L. cadenati and L. secutoris Pillai, 1963 . The first two of these species have already been distinguished from the new species on the basis of female characteristics. Females of the new species differ from L. cadenati in the form of leg 3, which has unfused endopodal lobes in the new species rather than endopodal lobes fused along the midline to form a triangular ventral plate in L. cadenati . In male L. cadenati leg 4 is about 4 times longer than leg 3 whereas in male L. pemphericola sp. nov. leg 4 is only about 1.8 times longer than leg 3. The ratio of the lengths of legs 3 and 4 is similar in males of L. secutoris and the new species, but the females differ: in L. secutoris the dorsal trunk plate is longer than the anterior trunk and conceals the genital complex, whereas in the new species the trunk plate is shorter than the anterior trunk and the genital complex is visible in dorsal view.