Boleophthalmus poti, Polgar & Jaafar & Konstantinidis, 2013

Polgar, Gianluca, Jaafar, Zeehan & Konstantinidis, Peter, 2013, A New Species Of Mudskipper, Boleophthalmus Poti (Teleostei: Gobiidae: Oxudercinae) From The Gulf Of Papua, Papua New Guinea, And A Key To The Genus, Raffles Bulletin of Zoology 61 (1), pp. 311-321 : 313-316

Boleophthalmus poti , new species

( Figs. 2 , 3 , 5 ; Tables 1, 2)

Material examined. — Holotype: MSNG 56891 , female, 89.9 mm SL; Papua New Guinea, Western Province, Fly river delta, Sisikura Island , 8°25'45.7"S, 143°36'24.0"E, coll. G. Polgar, A. Sacchetti & C. Tenakenai, 24 Sep.2007.

Paratypes: BMNH 2011.1 .27.1, 1 female (cleared and stained), 108.2 mm SL ; MSNG 56892 , 1 male and 1 female, 89.6–104.5 mm SL ; USNM 405556 , 3 males, 80.5–105.8 mm SL ; ZRC 52240 2 males and 1 female, 78.0–99.4 mm SL; same data as holotype . MSNG 56893 , 1 male, 99.5 mm SL; Papua New Guinea, Western Province, Fly river delta, Purutu Island, Wapi Creek , 8°23'21.0"S, 143°31'23.4"E, coll. G. Polgar, A. Sacchetti & C. Tenakenai, 23 Sep.2007 .

Non-type material: ZRC 51367, 2 ex., 35–50 mm, Purutu Island , Fly River delta, Papua New Guinea, 2007 ; ZRC 52249, 1 ex., 80.4 mm, same data as holotype .

Diagnosis. — Boleophthalmus poti is similar to B. birdsongi and B. caeruleomaculatus , sharing with these species unnotched, flattened and horizontally disposed dentary teeth. It is distinguished from these species (and all remaining congeners) by having elongate D1 fin spines, protruding from the fin margin, in both sexes and the following unique features of dorsal-fin colouration in live individuals: D1 with clearly demarcated sky-blue to whitish marginal band; interradial membranes of D1 greenish-brown, spotted with whitish to yellowish speckles, sometimes fused into broken, narrow and wavy lines; interradial membranes of D2 grey to pale brown, darker posteriorly, pale grey distally, with a very thin white margin and columns of 0–5 whitish spots between adjacent rays; D2 rays darker than interradial membranes.

Description. — General body shape as in Figs. 2 , 5C . Meristic and morphometric data are presented in Tables 1, 2. Head subcylindrical, about as wide as deep; body subcylindrical in thoracic region, becoming slightly compressed caudally; mouth subterminal, with jaw extending posteriorly to vertical point immediately posterior to posterior margin of eye. Lower jaw containing 2–8 caninoid teeth and 14–37 distally flattened, anteriorly directed and horizontally displaced teeth on each side. One recurved, canine tooth on both sides of mandibular symphysis, internal to the anterior margin of mandible ( Fig. 3 ). Posterior interorbital pore present. Anterior nare positioned at tip of triangular pendulous flap overhanging upper lip; posterior nare as slit immediately in front of anterior margin of eye. Anterior oculoscapular canal pores anterior to posterior nares, at ~1/3 the distance from eye to upper lip. Gill opening extending for ~4/5 of height of pectoral-fin base. All first-dorsal fin spines protruding from fin margin: elements III–V elongate, element IV longest in both sexes ( Figs. 2B , 5C ). In larger specimens, adpressed pectoral fin reaching a vertical point anterior to terminus of D1. Caudal fin ovate; pelvic fins completely fused into round disc with large pelvic frenum connecting pelvic spines, and basal membrane connecting innermost pelvic rays.

Live colouration. — Background colouration of dorsolateral portion of body and head yellowish-brown to greyish ( Figs. 2C , 5C ); ventral portion greyish and paler; in some individuals, isthmus, throat and thoracic region dark grey; scattered tiny whitish speckles covering head, extending anteriorly and dorsally from snout to insertion of D1; 8–10 subvertical, saddle-like, bilaterally asymmetrical and irregular dark brown bars on dorsum (2–3 before D 1, 2 in front and behind D1, and 4–5 below D2), saddle-like bars never extending below lateral midline; one horizontal, darker, irregular brownish band 1/3 width of body depth may be present on sides above lateral midline and below saddlelike bars, coursing from pectoral fins to caudal peduncle; sparse whitish speckles present on flanks; several scales on caudal peduncle with whitish margins. Caudal fin with grey interradial membranes and black rays. Anal fin with blackish rays and darkened inter-radial membrane, posterior portion more densely pigmented. Pectoral fins with translucent interradial membranes and pale brown rays, muscular base with similar colouration to body. Pelvic fins with translucent interradial membranes and pale brown rays, proximally dark grey, both dorsally and ventrally.

Preserved colouration. — Body colouration dorsally and laterally greyish, ventrally paler ( Fig. 2A, B ); isthmus, throat and thoracic regions grey, dark grey in some individuals. Small white speckles and vertical dark bars visible in preservation; on fins, live brown colour becoming grey and yellow whitish; live whitish pigmentation remains in preservation; other traits as in vivo.

Distribution. — Boleophthalmus poti is presently known only from the delta of the Fly River, in the Gulf of Papua ( Fig. 4 ).

Etymology. — The indigenous people of the Wapi villages of Purutu Island, the type locality, call this species ‘poti’, that in their language means ‘spotted’ and refers to the numerous tiny whitish spots present on the head of this species.

Remarks. — Freshly dead individuals of B. poti less than 5 cm SL (e.g., ZRC 51367) have a transparent, indistinct margin of D1, a much less densely pigmented D2 with columns of brownish spots on a transparent background, hyaline pelvic fins, scattered dark brown spots on the head and flanks on the anterior third of the body, and some irregular brown blotches on flanks, roughly corresponding to the dorsal saddle-like bands observed in larger specimens.

Boleophthalmus birdsongi was the only congener reported previously to possess flattened dentary teeth, lacking notches ( Murdy, 1989) but examination of all congeners revealed this tooth type is also present in B. caeruleomaculatus and B. poti .

Boleophthalmus poti differs from B. birdsongi ( Fig. 5A ) in having fewer interdorsal scale rows (3–6 vs. 6–9, respectively; Tables 1, 3), a longer D1 base (13–15% SL vs. 10–13% SL, respectively; Murdy, 1989; Tables 2, 4), and in the colouration of the unpaired fins: in the latter species, D1 is proximally black and distally blue; D2 has a narrow whitish basal portion, proximally and medially black, and a yellowish to whitish marginal band.

Boleophthalmus poti differs from B. caeruleomaculatus ( Fig. 5B ) in the smaller number of lateral-scale rows (97–119 vs. 130–151, respectively; Tables 1, 3), a shorter D2 base (40–43% SL vs. 43–48% SL, respectively) and a shorter pelvic disc (11–12%SL vs. 16–18%SL, respectively; Tables 2, 4; Murdy, 1989), in body colouration, which in the latter species includes sky-blue speckles on head, dorsum and flanks, and a sky-blue patch of skin below the orbits, and in the colouration of the unpaired fins: B. caeruleomaculatus lacks distinct marginal bands and has sky-blue spots on the interradial membranes, arranged in series along the whole length of rays.

Boleophthalmus caeruleomaculatus also attains a larger size than the other two species (maximum recorded size = 165 mm, vs. 111 mm and 106 mm of B. birdsongi and B. poti , respectively; Murdy, 1989; Takita et al., 2011; this study), and exhibits sexual dimorphism in the D1: females have elongated spines III–V, the IV being the longest one.

Multivariate analyses of meristic and morphometric datasets (n = 25; Tables 3, 4; Hammer et al., 2001) showed that B. birdsongi , B. caeruleomaculatus , and B. poti are morphologically distinct ( Fig. 6A, B ). Consistent with the above results, the length of D1 base and the pelvic fin length had higher PC1 and PC2 loadings (>0.5; Fig. 6B ).

Boleophthalmus poti is traditionally consumed and used as bait in the delta of the Fly River, together with the other mudskipper species B. caeruleomaculatus and Periophthalmodon freycineti Quoy & Gaimard (Polgar & Lim, 2011).

Figures

Fig.2. Boleophthalmus poti:A, holotype, MSNG 56891; B, paratype, preserved specimen, female (108.2 mm) (BMNH 2011.1.27.1); C, an individual in its natural habitat, on the mud banks of Wapi Creek, Purutu Island, Fly River delta. Scale bars =10 mm.

Fig. 3. Boleophthalmus poti, BMNH 2011.1.27.1. Lateral view of the suspensorium. Abbreviations: ap = autopalatine; d = dentary; ep = ectopterygoid; hm = hyomandibular; io = interopercle; m = maxilla; mp = metapterygoid; op = opercle; pm = premaxilla; po = preopercle; pp = ascending processes of the premaxilla;q =quadrate; sop = subopercle; sp = symplectic; st = symphyseal tooth. Scale bar = 1 mm. the original image was reversed horizontally.

Fig. 5. Shape and colouration of freshly dead species of Boleophthalmus with un-notched dentary teeth: A, female of B. birdsongi (95 mm; ZRC 52250); B, female of B. caeruleomaculatus (106 mm; MSNG 54689); and C, paratype, male of B. poti (83.4 mm; USNM 40566). Scale bars = 10 mm.

Fig. 4. Geographical distribution of the species of Boleophthalmus: point data; bird = Boleophthalmus birdsongi; bodd = Boleophthalmus boddarti; caer = Boleophthalmus caeruleomaculatus; duss = Boleophthalmus dussumieri; pect = Boleophthalmus pectinirostris; poti = Boleophthalmus poti. Data from Murdy, 1989; Swennen et al., 1995; Rainboth, 1996; Takita et al., 1999; Nakabo, 2002; Nanami & Takegaki, 2005; Chen et al., 2007; Froese & Pauly, 2007; Ocean Biogeographic Information System, 2007; Baeck et al., 2008; Global Biodiversity Information Facility, 2008; Larson et al., 2008; Polgar & Crosa, 2009. Data in online databases were verified by comparison with museum material and published references.

Fig. 6. Multivariate morphological analyses of the three species of Boleophthalmus without notched dentary teeth, supporting the separation of the examined specimens in 3 morphologically distinct groups.A: PCO scatter plot of meristic characters, after logarithmic transformation. The two coordinate axes Coord 1 and Coord 2 explained the highest percentage of total variance (in parentheses); closed lined (convex hulls) delimit clusters of specimens of the same species. B: PCA distance biplot of morphometric characters after Darroch & Mosimann transformation (1985). The two principal component axes PC1 and PC2 explained the highest percentage of total variance (in parentheses); closed lines (convex hulls) delimit clusters of specimens of the same species; the variables are projected onto the scattergram as vectors, graphically visualising their PCA loadings, or the degree they enter into the principal components. PLVL separates caer from bird and poti, while D1BL separates bird from caer and poti. bird = B. birdsongi (n = 11); caer = B. caeruleomaculatus (n = 4); poti = B. poti (n = 10). See Tables 3, 4 for the dataset.