Marcenendius NavÁs, 1913

Lienhard, Charles & Baz, Arturo, 2011, Redescription of the genus Marcenendius Navás (Psocodea: ‘ Psocoptera’: Amphientomidae) with a key to western Palaearctic amphientomids, Revue suisse de Zoologie 118 (3), pp. 451-466 : 453-454

Marcenendius NavÁs, 1913

Marcenendius NavÁs, 1913: 334 . Type species (by original designation): Marcenendius nostras NavÁs, 1913: 334 .

REVISED DIAGNOSIS: Belonging to Amphientomidae . Forewings densely covered with scales ( Figs 1 , 5c ). Median ocellus close to postclypeus, smaller than lateral ocelli, always present in fully-winged forms, occasionally strongly reduced or absent in brachypterous forms; lateral ocelli widely separated, close to compound eyes. Antenna with 14 articles (i. e. 12 flagellomeres), rarely the two apicalmost flagellomeres fused. P2 only with simple, short hairs, lacking spur sensillum and macrochaetae ( Fig. 6c ). Mandibles of normal shape ( Fig. 6a ). Distal half of labrum with a pair of well-sclerotized longitudinal labral rods, originating from labral nodes ( Keler, 1966: nodus labralis) on internal face of labrum and running parallel to each other in about 1/3 of its width from lateral margin ( Fig. 2e ). Phallosome Y-shaped, with a slightly sclerotized longitudinal internal zone on each side in apical half ( Fig. 3d ). Internal T-shaped sclerite of female subgenital plate present but occasionally strongly reduced ( Figs 2d , 3a , 6d ). Nymphs with dorsal side of abdomen and thorax (including wingpads) densely covered by characteristically curled "corkscrew" hairs ( Fig. 6b ).

SPECIES ASSIGNED TO MARCENENDIUS : Marcenendius nostras NavÁs, 1913 ; Marcenendius fortunatus ( NavÁs, 1917) comb. nov. from Nephax ; Marcenendius angolensis ( Badonnel, 1955) comb. nov. from Nephax .

DISCUSSION: NavÁs' descriptions concerning his genus Marcenendius are rather superficial ( NavÁs, 1913, 1923), but he mentions one character that is really diagnostic within western Palaearctic amphientomids, i. e. the presence of three widely separated ocelli (see NavÁs, 1923). In the only other amphientomid genus of this region, Nephax Pearman , the median ocellus is absent. Several macropterous amphientomids recently collected in continental Spain and on the island of Mallorca correspond to NavÁs' description with respect to this ocellar character. In the following we explain briefly why we tentatively assign these specimens to the genus Marcenendius and in particular to its type species Marcenendius nostras .

The venation of forewing and hindwing figured by NavÁs (1913, 1923) corresponds to macropterous individuals and is very similar to that observed in the new material, except for the presence of only one anal vein in the figure given by NavÁs (1913) for M. nostras . We interpret this as an inaccuracy of NavÁs' figure (in Amphientomidae two anal veins are always present; see Smithers, 1972). The shape of the apex of forewing and hindwing seems to be somewhat variable in Marcenendius , broadly rounded ( NavÁs, 1913: hindwing; Navas, 1923: forewing) or slightly acuminate ( NavÁs, 1913: forewing; NavÁs, 1923: hindwing). The wings of the new material are about intermediate in shape ( Fig. 2a, b ). In NavÁs' figures of forewings the veins CuP and A1 reach the wing margin separately (nodulus absent). This condition is rather unusual in Amphientomidae where CuP and A1 generally end together on wing margin, forming the nodulus (see Smithers, 1972). But absence of nodulus has also been observed in the brachypterous and macropterous amphientomids previously known from western Palaearctic (see Lienhard, 1998, 2009). In the new material from continental Spain and Mallorca the distal part of A1 is usually very faint and curved towards CuP near wing margin, meeting the latter on the margin (nodulus); this situation could be confirmed on several slide-mounted forewings ( Fig. 2a ). However, at low magnification A1 seems to end in the membrane, almost parallel to CuP. Thus, the absence of a nodulus in NavÁs' figures is probably due to inaccurate drawing (i. e. incorrect extrapolation of the faint distal part of A1).

The presence in Spain (Alicante, Almeria, Malaga and Mallorca) of an amphientomid species not belonging to the genus Nephax and showing some characters mentioned by NavÁs (1913, 1923) for his genus Marcenendius is here considered as sufficient for redescribing the genus based on this new material, which is tentatively assigned to the type species M. nostras . Marcenendius is well-defined by a striking autapomorphy of nymphs, the presence of "corkscrew" hairs on dorsal side of thorax and abdomen ( Fig. 6b ), a kind of setae previously unknown in Psocoptera . These hairs were present in the nymphs from Alicante, Almeria and Mallorca ( M. nostras ) and also in nymphs from different localities on Canary islands which belong to a second species of Marcenendius , M. fortunatus (NavÁs) comb. nov. (see also discussion of this species, below).

Meinander (1973) already considered the African species Nephax angolensis Badonnel as "evidently congeneric" with M. fortunatus (NavÁs) when redescribing the latter as Nephax fortunatus . Because there is no doubt that this Macaronesian species belongs to the newly defined genus Marcenendius , we formally transfer also the African species to this genus, M. angolensis (Badonnel) comb. nov. According to the description by Badonnel (1955) it differs from both western Palaearctic species by the absence of a stigmapophysis in forewing and by the particular shape of the T-shaped sclerite of the female subgenital plate and of the lacinial tip.

For discussion of differences in forewing venation between macropterous and brachypterous amphientomids, see genus discussion of Nephax Pearman , below.

Figures

FIG. 1

FIG. 5. Marcenendius nostras NavÁs: (a) Biotope (dry river bed) of the Alicante specimens (Peñas Roset). (b) General view of Peñas Roset. – Marcenendius fortunatus (NavÁs): (c) Female from Fuerteventura island (Canary Islands), near Lajares, 15.xi.1998, habitus in dorsolateral view, body length 2.5 mm. (d) Biotope of this specimen (stone wall built by humans). Photographs: V. M. Ortuño (a, b), C. Lienhard (c, d).

FIG. 6

FIG. 2

FIG. 3