Moribaetis maculipennis ( Flowers 1979 )

Kluge, Nikita J. & Bernal Vega, Juan A., 2018, Redescription of the Central American genus Moribaetis Waltz & McCafferty 1985 (Ephemeroptera, Baetidae), Zootaxa 4521 (2), pp. 231-257 : 237-247

Moribaetis maculipennis ( Flowers 1979)

( Figs 1–61 )

Baetis maculipennis Flowers 1979: 187 (male imago, larva). Moribaetis maculipennis: Waltz & McCafferty 1985: 245 , figs 5, 26–27 (larva) (non fig. 32); McCafferty & Lugo-Ortiz 1998: 120 (key to male imagoes).

Material examined. PANAMA, provincia de Bocas del Toro, bosque protector Palo Seco, Altos del Valle , río Buris (8°47'37''N, 82°11'35''W), 24–29.I.2018, coll. N. Kluge & L. Sheyko: 4 L-S-I ♂ , 5 L-S ♂, 11 L-S-I ♀, 2 L-S ♀, 99 larvae ( ZIN) ; provincia de Chiriquí, reserva forestal Fortuna, quebrada Honda (8°45'2.15''N, 82°14'18.68''W), 11.XI.2017, coll. J. Bernal & T. Ríos: 5 larvae ( UNACHI) ; Alambique, río Fonseca (8°22'28.15''N, 82°4'28.91''W; 8°22'1.46''N, 82°4'28.65''W), 7.XII.2016, coll. T. Ríos: 9 larvae ( UNACHI) .

Diagnosis. Larva. Described by Flowers (1979) and Waltz & McCafferty (1985). Differs from M. latipennis sp. n. by following characters.

(1) Larval head elongated and narrowed, with antennae bases brought together, frons narrow and keel-shaped ( Figs 12–13 ). In specimens with intensively developed cuticular coloration, cuticle of frons in last larval instar brown ( Fig. 12 ), in previous instars colorless ( Fig. 13 ) [other cuticular coloration as characterized for Moribaetis (18)].

(2) Both left and right mandibles with incisor [blade-like – see Moribaetis (2)] and kinetodontium completely fused together and lacking denticles; prosthecae of both mandibles equally diminished and very slender [see Moribaetis (3)] ( Figs 18–21 ).

(3) Femur of fore leg parallel-sided ( Fig. 25 ); stout setae on its inner side pointed, occupy wide area ( Fig. 33 ).

(4) Dark brown submedian hypodermal stripes on abdominal terga VI–VIII equally narrow, stripes on terga III–IV also not widened ( Figs 1, 3 ).

(5) Posterior margins of abdominal sterna I–IV without denticles, that of sterna V–IX with regular pointed denticles [II–X terga with larger denticles – see Moribaetis (14)].

(6) Paraproct with denticles on inner and apical margins sharply differentiated: minute on inner margin and significantly larger on apical margin ( Flowers 1979: fig. 16).

(7) Larval cerci and their swimming setae unicolor ( Fig. 1 ).

Male imago. Described by Flowers (1979). Differs from M. latipennis sp. n. and M. salvini by following characters.

(1) Turbinate eyes low and wide, contiguous both in imago and in subimago ( Figs 34–35 , 48–50 ) (in contrast to narrow in M. latipennis ).

(2) On fore wing most cross veins light yellow, lighter than adjacent brown maculae (in contrast to dark brown in M. salvini ); brown maculae present all over wing, forming nearly regular bands ( Figs 48–50 ). Hind wing often also with brown maculae, variably located ( Fig. 55 ).

(3) Dark brown submedian hypodermal stripes on abdominal terga VI–VIII equally narrow ( Fig. 48 ) (in contrast to M. latipennis ).

(4) Femur with small contrasting brown spot on posterior side ( Fig. 50 ) (in contrast to wide brown band in M. salvini – Fig. 102 ).

Female imago. Coloration of body, wings, legs and cerci as in male ( Figs 53–54 ). Fore tarsus with apical spines on 2nd and 3rd segments (as in Fig. 31 ) (as on middle and hind tarsi – as in Fig. 32 ).

Eggs. Oval, covered with thick coat ( Fig. 56 ). Outer surface of coat forms folds and regularly arranged round protuberances, each protuberance with concavity at middle ( Figs 57–59 ). Chorion under the coat with dense fine concavities ( Figs 60–61 ).

Dimensions. Fore wing length 7.5–9.2 mm (7.5–8.5 in our specimens, 9.0–9.2 according to Flowers 1979).

Distribution. Costa Rica and Panama.

Comparison. Imago of Moribaetis maculipennis differs from the earlier described M. salvini by coloration of wings, which in M. maculipennis have brown markings all over fore wing and cross veins yellow, lighter than adjacent brown markings ( Figs 48–50 ), while in M. salvini brown markings are present only on anterior part of fore wing, and cross veins are brown, darker than adjacent brown markings ( Fig. 102 ). The formerly reported difference between these species in coloration of cerci is wrong (see «Comments»).

Comments. Originally, male imagoes and larvae of this species were reliably associated based on one male imago reared from larva (Flowers 1989). Recent rearing of imagoes of both sexes allows to add here description of female and egg.

In the original description tergalius IV is figured greatly widened and angulate ( Flowers 1979: fig. 14), that somewhat differs from our specimens ( Fig. 8 ).

The original description ( Flowers 1979), does not provide comparison of the new species B. maculipennis with the earlier described species B. salvini Eaton 1885 . Comparison of these two species was given by Waltz & McCafferty (1985), who reexamined the lectotype of B. salvini . These authors did not add any new characteristics for male imago of Baetis salvini and reported only that it was «Adequately characterized by Eaton (1885)» ( Waltz & McCafferty 1985: 247). In their diagnosis and the key to male imagoes, M. maculipennis is distinguished from M. salvini by three characters only: number of intercalaries of hind wing, «the abdominal color pattern» and coloration of cerci. Actually, no one of these characters allows to distinguish these two species:

Hind wing of Moribaetis normally has one intercalary between branches of the second vein ( Flowers 1979: fig. 3). Hind wing of M. salvini was characterized as «usually with two distinct intercalaries and two or three minor intercalaries (fig. 44)». The figures of fore and hind wing of M. salvini ( Waltz & McCafferty 1985: figs 43–44) were redrawn from the figures of the right fore and hind wings of the lectotype in the original description (Eaton 1885: pl. 16: figs 29a); no other winged specimens reliably attributed to M. salvini have been ever examined. Additional intercalary is present on individual hind wings of M. maculipennis ( Fig. 55 ), so M. maculipennis and M. salvini have no difference by this character. McCafferty & Lugo-Ortiz (1998) wrote «It is possible that the number of marginal intercalaries between the forks of the second elongate vein in the hindwings is variable within M. macaferti , ... and thus we do not recommend attempting to identify adults of species of Moribaetis on that basis».

Waltz & McCafferty (1985) did not report, which feature of «the abdominal color pattern» distinguishes M. maculipennis from M. salvini ; the imaginal color pattern, being hypodermal, should be the same in imago and larva; the figure of larva, which illustrates this color pattern for M. maculipennis ( Waltz & McCafferty 1985: fig. 32), actually belongs to M. latipennis sp. n., whose larva was wrongly attributed to M. salvini (see below).

Waltz & McCafferty (1985) stated that imago of M. maculipennis differs from M. salvini by coloration of cerci, which in M. maculipennis are «(fig. 33) banded in alternating pattern of one white segment with three darkened segments» and in M. salvini are «(fig. 42) banded in alternating pattern of one lightly darkened segment with three white segments». This feature of M. maculipennis was rewritten from the original description (Flowers 1 979: 188), but illustrated differently: cercus is figured as having alternating two darkened segments and two white segments ( Waltz & McCafferty 1985: fig. 33); according to the original description, «all segments darker brown at apex», while on this figure apices of segments are not darkened. The paratype, from which this figure was done, was not reared, so its systematic position is unknown. All our specimens reared from larvae have apex of each cercal segment contrastingly darkened, and each 4th segment is more or less darker than others ( Figs 42–43 ). This coloration is the same as in the lectotype of M. salvini ( Fig. 103 ; Waltz & McCafferty 1985: fig. 42).

Redescription and drawings of M. maculipennis made by Waltz & McCafferty (1985) belong to this species, except for the drawing of larval thorax and abdomen ( Waltz & McCafferty 1985: fig. 32); judging by its color pattern, the larva drawn on this figure belongs not to B. maculipennis , but to M. latipennis sp. n., which in the same paper was described as « M. salvini » (see below). The authors of this paper wrote that «Larvae of M. maculipennis may be easily separated from other species of this genus by the distinctive abdominal color pattern (fig. 32)»; actually the abdominal color pattern shown on this figure is hypodermal, so it is the same in larva and imago. Abdominal color pattern of imago of M. maculipennis is adequately figured in the original description ( Flowers 1979: fig. 5); in contrast to M. latipennis sp. n., its paired stripes on abdominal tergum VI are not widened, being similar to the stripes on abdominal tergum VII ( Figs 1, 3 ).

Waltz & McCafferty (1985) stated that larva of M. maculipennis differs from « M. salvini » (actually M. latipennis sp. n.) by having «frons with distinct medial pigmented area between ocelli» ( Waltz & McCafferty 1985: 250, fig. 5). Actually, pigmentation of larval frons in both these species is present only within cuticle, but not in underlying tissues, so it is absent at the beginning of each instar; in M. maculipennis cuticle of frons becomes dark only in the last larval instar ( Fig. 12 ), being colorless during in all previous instars ( Fig. 13 ).

Figures

FIGURES 1–15. Larvae of Moribaetis maculipennis. 1–2, last instar male larva, dorsal and lateral view (with hypodermal and cuticular coloration combined); 3, just moulted female larva (with hypodermal coloration only); 4, part of its exuviae from abdomen (with cuticular coloration only); 5–11, tergalii of pairs I–VII; 12, head of last instar male larva; 13, the same, penultimate instar; 14, fragment of cercus with detached swimming setae, view from median side; 15, fragment of costal rib of tergalius. Abbreviations: I–X, abdominal terga.

FIGURES 16–21. Mandibles of Moribaetis maculipennis. 16–17, left and right mandibles before moult to next (last) instar, with new mandibles visible inside; 18–21, left and right mandibles of last instar larva just after moult and their fragments enlarged. Abbreviations: kd, kinetodontium; prs, prostheca.

FIGURES 22–24. Larva of Moribaetis maculipennis. 22, labium (at left ventral view, at right dorsal view); 23, claw (anterior view); 24, its cross section. Abbreviation: d-m, seta of dorso-median row.

FIGURES 25–33. Legs of Moribaetis maculipennis. 25–27, larval fore, middle and hind legs; 28, fragment of fore tibia of female subimago; 29, the same, another specimen; 30, fragment of middle tibia of female subimago; 31–32, fragments of fore and middle leg of female subimago; 33, fragment of femur of larval fore leg (25–27 and 29–32, the same individual). Abbreviation: pt-ti, patella-tibial suture.

FIGURES 34–43. Moribaetis maculipennis. 34–35, male subimago just after moult; 36, abdominal sternum IX of last instar male larva with gonostyli visible inside; 37, gonostyli of male subimago; 38, exuviae of subimaginal gonostyli; 39, genitals of male imago; 40, caudalii of last instar larva with crumpled sibimaginal cerci visible inside; 41–42, proximal part of imaginal cercus and its subimaginal exuviae (arrows show correspondence of their joints); 43, proximal part of imaginal cercus of another specimen.

FIGURES 44–47. Genital of Moribaetis maculipennis. 44, hind margin of IX sternum of mature larva and subimaginal gonostyli crumpled under larval cuticle (specimen with fully developed subimaginal wings); 45, gonostyli crumpled under larval cuticle just before moult to subimago; 46, exuviae of subimaginal gonostyli; 47, genitals of male imago (ventral view; muscles and internal sclerites shown by interrupted lines). Abbreviations: gs1, gs2, gs3, segments of gonostylus; gv, gonovectis; m.IX-X, intersegmental muscle going from base of IX sternum to base of paraproct; m.sg, sterno-styligeral muscle; pgs, larval protogonostylus; us, unistyliger.

FIGURES 48–52. Moribaetis maculipennis. 48–50, male imago; 51, subimaginal exuviae of left postsubalar sclerite and lateropostnotal crest; 52, subimaginal exuviae of left half of mesonotum.

FIGURES 53–55. Moribaetis maculipennis. 53–54, female imago; 55, hind wing.

FIGURES 56–61. Eggs of Moribaetis maculipennis. 56, view in transmitted light; 57–59, eggs covered with coat; 60–61, egg without coat.

FIGURES 102–105. Moribaetis salvini (lectotype, photo by Ben Price). 102, lateral view; 103, fragment of cercus; 104, dorsal view and tube with genitals; 105, labels.