Lacustricola myaposae (Boulenger, 1908)

Braganca, Pedro H. N., Zeeventer, Ryan M. van, Bills, Roger, Tweddle, Denis & Chakona, Albert, 2020, Diversity of the southern Africa Lacustricola Myers, 1924 and redescription of Lacustricola johnstoni (Guenther, 1894) and Lacustricola myaposae (Boulenger, 1908) (Cyprinodontiformes, Procatopodidae), ZooKeys 923, pp. 91-113 : 91

Lacustricola myaposae (Boulenger, 1908) Figures 7 , 8

Haplochilus myaposae Boulenger 1908:232 [original description: Myaposa River, Zululand, KwaZulu-Natal, South Africa].

Material examined.

BMNH 1907.4.17.88, Lectotype; Myaposa River, Kwazulu-Natal, South Africa. Examined by photographs and x-rays. SAIAB 96619, 10 (2 C&S), 18.1-27.9 mm SL; Mhlathuze, KwaZulu-Natal, South Africa 28°50'18"S, 31°54'41"E; col: B. Ellender, O. Weyl & R. Karsing; 27 May. 2010. - SAIAB 88658, 31 (6 C&S), 21.3-38.0 mm SL; Bridge at Mseleni, KwaZulu-Natal, South Africa, 27°21'49"S, 32°31'33"E; col: B. Kramer, E. Swartz, P.T. Maake; 31 Oct. 2009. - SAIAB 96560, 1, 30.2 mm SL; Nseleni River Nature Reserve, KwaZulu-Natal, South Africa, 28°41'57"S, 32°0'4"E; col: R. Jones, O. Weyl; B. Ellender & R. Karsing; 23 May. 2010. - SAIAB 86637, 1, 34.0 mm SL; St Lucia area 2, KwaZulu-Natal, South Africa, 28°20'44"S, 32°21'14"E; col: R. Karssing, J. Craigie, S. Khubela, R. Ndlhovu, A. Xoswa; 08 Sep. 2009. - SAIAB 47128, 1, 40.5 mm SL; KwaZulu-Natal, South Africa; 31 Jan. 1989. - SAIAB 83143, 2, 38.1-38.2 mm SL; Greater St Lucia Wetland Park, Ozabeni, Ovalweni crossing, KwaZulu-Natal, South Africa, 27°38'59"S, 32°38'9"E; col: J.D. Craigie & R. Karssing; 29 May. 2007. - SAIAB 96591, 9 (2 C&S), 21.1-36.2 mm SL; Upper Nseleni in sugar Estate, Richards Bay, KwaZulu-Natal, South Africa, 28°40'27"S, 31°57'51"E; col: B. Ellender, O. Weyl & R. Karsing; 24 May. 2010. - SAIAB 83149, 3, 34.7-38.1 mm SL; Greater St Lucia Wetland Park, Ozabeni, Samango crossing, KwaZulu-Natal, South Africa, 27°37'3"S, 32°33'2"E; col: N. Rivers-Moore & R. Karssing; 30 May. 2007. - SAIAB 208915, 6; Makat Farm in Jamela, Mposa River, a tributary of the Nseleni River, KwaZulu-Natal, South Africa, 28°39'18"S, 32°01'48"E; col: A. Chakona, N. Mazungula & B. Motshegoa; 4 Sep. 2015.

Diagnosis.

" Lacustricola " myaposae is distinguished from all congeners from the " L. " katangae clade by the absence of a zigzag black mark along the flank (vs. presence); and from congeners belonging to the " L. " hutereaui clade by the absence of barred dorsal, anal and caudal-fins and also by the absence of a conspicuous reticulate pattern on scales margin. It is further distinguished from all congeners except " L. " johnstoni and " L. " moeruensis by the presence of an orange dorsal, anal and caudal-fins in females (vs. hyaline); it is distinguished from " L. " johnstoni and " L. " moeruensis by the presence of light purple colouration in the posterior region of flank (vs. absence); an orange pectoral-fin in males (vs. hyaline); and by a distinct colouration pattern in both dorsal and anal-fins in which melanophores become continuously more concentrated close to fin margins, forming a grey zone before the margin become entirely dark (vs. absence of this colouration pattern). " Lacustricola " myaposae is further distinguished from " L. " johnstoni by a deeper body profile, males body depth 26.0-30.9% of SL (vs. 20.6-24.4%of SL), females body depth 22.8-25.1% of SL (vs. 19.7-22.5% of SL); a longer dorsal-fin base length in males 11.9-13.1%of SL (vs. 8.7-11.6% of SL) and in females 10.8-11.6% SL (vs. 7.3-10.1% SL); and a deeper head in males 70.7-79.8% of HL (vs. 61.9-67.0% of HL) and in females 66.6-69.6% of HL (vs. 59.4-63.5% of HL). Other morphometric characters presenting a slight overlap but useful in distinguishing " L. " myaposae from " L. " johnstoni are: a deeper caudal peduncle, 14.0-17.1% of SL in males and 12.9-13.7% of SL in females (vs. 12.6-14.5% of SL in males and 11.2-12.7% of SL in females); a shorter caudal-fin, 27.5-30.2% of SL in males and 25.3-28.5% of SL in females (vs. 30.1-33.8% of SL in males and 28.9-31.2% of SL in females); and a deeper head, 63.1-67.9% of HL in males and 65.3-68.1% of HL in females (vs. 57.1-63.2% of HL in males and 59.0-64.7% of HL in females).

Description.

Morphometric data are presented in Table 1 . Maximum recorded adult size 39.0 mm SL. Dorsal profile of body approximately straight to slightly convex from snout tip to dorsal-fin origin; convex along dorsal-fin base, and nearly straight on caudal peduncle. Ventral profile convex from lower jaw to beginning of anal-fin base; slightly convex along the anal-fin base and nearly straight on caudal peduncle. Caudal peduncle slightly deeper in males. Anterior portion of body laterally compressed, becoming more compressed behind anal-fin origin.

Dorsal-fin rounded in males not reaching caudal-fin base; its origin in vertical between 6th and 7th anal-fin rays. (Fig. 7 ) Anal-fin rounded in males, tip not reaching vertical through dorsal-fin tip. Dorsal and anal-fins are not elongated in females. Caudal-fin slender. Pectoral-fin elliptical, its posterior margin reaching vertical just behind pelvic-fin base. Pelvic-fin length in males longer than in females, reaching urogenital papillae aperture; short in females, tip reaching region just before urogenital opening. Pelvic-fin bases medially separated by interspace broader than width of each pelvic-fin base. Dorsal-fin rays 8(7), 9(20), 10(10) and 11(2); anal-fin rays 12(1), 13(9), 14(14) and 15(15); caudal-fin rays 20(3), 21(7), 22(9), 23(6), 24(9), 25(3) and 26(1); pectoral-fin rays 11 (2), 12(18) and 13(19); pelvic-fin rays (6).

Frontal squamation G-patterned (Fig. 5 ). Head neuromasts placed in shallow grooves. Cephalic lateral line system: anterior portion of supraorbital sensory canal open, with three neuromasts, anteriormost one anteriorly displaced from the other two; posterior portion open, with three exposed neuromasts; anterior infra-orbital canal partially closed, with three pores and one free neuromast, but in juveniles and subadults all anterior infraorbital canal can be opened with three exposed neuromasts; median portion of infra-orbital region with series of eight to nine minute neuromasts; posterior infra-orbital canal closed, with two pores; preopercular canal closed in both dorsal and ventral portions with seven pores; mandibular canal represented by two neuromasts, one in vertical through corner of mouth and the other anteriorly positioned in the lower jaw ventral portion. Longitudinal series of scales 26(14), 27(11), 28(8), 29(1); transverse series of scales (7); circumpeduncular scales (10); predorsal scales 16(17), 17(16), 18(3).

Osteology.

Osteological structures are presented in Fig. 6 . Mesethmoid and vomer absent. Frontals, anterior margin, extending anteriorly between nasals. Parasphenoid medial process short, not contacting pterosphenoid; anterior margin rounded. Lateral ethmoid overlapping with anterior portion of parasphenoid. Posterior process of supraoccipital long, reaching first vertebra. Lachrymal rectangular. Premaxillary and dentary teeth well developed. Retroarticular triangular or subtriangular. Dentary deep. Dorsal process of maxilla broad overlapping the ascending process of premaxilla; ventral process greatly reduced, consisting of a rounded ventromedial bulge. Ventral arm of maxilla broad, laterally expanded. Medial surface of premaxilla ascending process with a straight or slightly concave profile. Entopterygoid posterior portion and sympletic bone keel deep. Opercle triangular, anterodorsal process present. Anterior process of anterior ceratohyal does not extend ventraly to ventral hypohyal. Urohyal ventral margin concave. First and second basibranchials with expanded lateral bone flanges. Cartilaginous portion of basihyal shorter than osseous portion. Fourth ceratobranchial anterior third with teeth. Second pharyngobranchial plate with teeth. First epibranchial base, broad, more than three times anterior portion width. Supracleithrum rounded. Posttemporal rod-like, ventral arm absent. Cleithrum bony flange not covering scapula foramen. Ventral postcleithrum slender, similar in width to adjacent first pelural rib. Basipterygium, posterior process, shorter or about the same size of medial process. Anal-fin proximal radials about the same length and parallel to each other. Hypurals completely fused. Parahypural proximal end overlapping the preural centrum. Total vertebrae 28(1), 29(8) and 30(1), precaudal 12(9) and 13(1) and caudal 16(2), 17(7) and 18(1). First proximal radial of dorsal-fin between neural spine of vertebrae 13 and 14. First proximal radial of anal-fin between pleural rib of vertebrae 11 and 12. Gill rakers on first branchial arch 9(1), 10(2) and 11(1). Branchiostegal rays 5.

Colouration in alcohol.

Overall colouration of body pale brownish yellow with minute chromatophores sparsely distributed, and some organised chromatophores forming an inconspicuous reticulate pattern along margins of flank scales, more conspicuous along the longitudinal series of scales on mid-body line of flank (Fig. 7 ). Ventral surface scarcely pigmented. Pale brown chromatophores along whole mid-body line of flank. Head overall colouration yellowish brown. Dark brown chromatophores on dorsum of head. Minute chromatophores concentrate in the lower jaw and pre-orbital region, forming a distinct darker region. Iris silver, darker close to pupil; dark pigment concentrated on dorsal margin of eye. All fins hyaline in females, with melanophores sparsely concentrated only on fins membranes and along fin rays; high concentration of melanophores on males dorsal-fin, with small hyaline spots on fin membrane, close to rays insertion; dorsal-fin margin dark; melanophores on anal-fin becoming continuously more concentrated close to fin margin; region close to anal-fin rays insertion hyaline; caudal-fin with conspicuous dark blotches in the middle rays that could be organised in distinct bands or not, melanophores on fin distal portion becoming continuously more concentrate close to fin margin; pelvic-fin dark, with numerous small chromatophores; pectoral-fin with chromatophores sparsely concentrated on fins membranes and along fin rays. Female urogenital opening pocket scales with few sparse dark brown chromatophores.

Colouration in life.

Males (Fig. 8A ). Flanks yellow brown, scattered with yellow-green metallic dots along the flank; posterior region of flank purple, more conspicuous posteriorly on caudal peduncle. Small cupric iridescent blotch on flank region just posterior to pectoral-fin. Dorsum yellow-brown. Ventral surface white between lower jaw and opercle margin; light yellow between opercle margin and urogenital opening; greyish brown between urogenital opening and caudal peduncle. Side of head predominantly bluish silver, dorsal portion yellow-brown, post-orbital region with a distinct green bright blotch. Iris dark grey, light yellow close to pupil. Eye bright silver on dorsal portion. Lower jaw and pre-orbital region dark brown-grey, forming a distinct horizontal band. Pectoral-fin base hyaline, distal portion orange; pelvic-fin yellow with dark chromatophores on fins tip; anal-fin with two orange-brown rows and melanophores on becoming continuously more concentrate close to fin margin; dorsal-fin orange-yellow with two-three dark bars on its posterior portion, margin black; caudal-fin orange-yellow with three vertical bands that could be organised in distinct bands or not, melanophores on fin distal portion becoming continuously more concentrate close to fin margin.

Females (Fig. 8B ). Flanks bright blue, scattered with green metallic dots along the flank; posterior region of flank purple, more conspicuous posteriorly on caudal peduncle. Cupric iridescent blotch on region just posterior to pectoral-fin. Dorsum yellow-brown. Venter white between head and pelvic-fin insertion; bright blue between pelvic-fin and end of caudal-fin; grey on caudal peduncle. Scales around urogenital opening covered with dark chromatophores. Side of head predominantly bluish silver, ventral portion white, dorsal portion yellow-brown, post-orbital region with a distinct green bright blotch. Iris dark grey, light yellow close to pupil. Eye bright silver on dorsal portion. Lower jaw and pre-orbital region dark brown-grey, forming a distinct horizontal band. Pectoral-fin first rays orange-brown; pelvic-fin hyaline, with a faint orange colouration on fin base; dorsal-fin orange, distal margin hyaline; anal-fin base hyaline, distal portion orange; caudal-fin orange, distal region hyaline.

Distribution and habitat.

" Lacustricola " myaposae is only known from the coastal river drainages and lacustrine systems in Kwazulu-Natal Province of South Africa to coastal lagoons south of the Maputo River in Mozambique (Fig. 2 ). The species is usually found associated with marginal vegetation along the banks of small and large rivers in freshwater. Despite occurring in a coastal area, little is known about the salinity tolerance capacity of " L. " myaposae .

Remarks.

Only one specimen was found among the syntypes (original catalogue number BMNH 1907.4.17.88-89) of " Lacustricola " myaposae , one specimen is missing (pers. comm. James Maclaine), thus this remaining individual was designated as the Lectotype (BMNH 1907.4.17.88).

Figures

Figure 2. Southern Africa " Lacustricola " distribution maps. Spots correspond to the exact localities for the haplotypes included in this study, and the shaded area refers to the inferred distribution for each species. Map A yellow - " Lacustricola " hutereaui; grey - " L. " johnstoni; brown - " L. " myaposae; and purple - " L. " jubbi. Map B dark green - " L. " macrurus; orange - " L. " mediolateralis; red - " L. " katangae; light blue - " L. " centralis; blue - " L. " aff. johnstoni ' Okavango'; light green - " L. " aff. johnstoni ' Congo'.

Figure 5. Cephalic pores and head squamation pattern: A, B head dorsal and lateral view of " L. " johnstoni C head lateral view of " L. " myaposae.

Figure 6. Osteological plate of " L. " johnstoni (SAIAB 35820) from the Upper Shire River, Mangochi, Malawi. A Lachrymal B neurocranium, ventral view C neurocranium dorsal view D ventral post-cleithrum and first pleural rib, lateral view E anal-fin radials and proximal radials, left lateral view F caudal-fin skeleton, left lateral view G dorsal-fin radials and proximal radials, left lateral view H left branchial arches ventral portion, ventral view I right dorsal portion of branchial arches, ventral view J urohyal, left lateral view K left basipterygium, dorsal view L left shoulder girdle, lateral view M right hyoid bar, lateral view N left jaws, jaws suspensorium and opercular apparatus, lateral view. Scale bars: 1 mm.

Figure 7. " Lacustricola " myaposae preserved colouration: A male SAIAB 96591, 31.7 mm SL B female SAIAB 96591, 35.7 mm SL; from Nseleni River, KwaZulu-Natal, Republic of South Africa.

Figure 8. " Lacustricola " myaposae colouration in life: A male SAIAB 208915, 33.0 mm SL B female SAIAB 208915, 35.2 mm SL; from Nseleni River, KwaZulu-Natal, Republic of South Africa.