Redescriptions, Lectotype Designations, New Synonyms and New Geographic Records for the “Tiger” Species of Mycotretus Lacordaire, 1842 (Coleoptera: Erotylidae: Tritomini)

The Neotropical Mycotretus Lacordaire, 1842 is one of the largest and most widespread genera of the Erotylidae, encompassing more than 200 described species. Among the species with a similar body coloration, there is a “group” of six valid species—called here the “tiger” Mycotretus—that possess several pronotal and elytral black spots, as follows: M. tigrinus (Olivier, 1792); M. multimaculatus Taschenberg, 1870; M. centralis Arrow, 1909; M. tigrinoides Mader, 1942; M. tigripennis Mader, 1942; and M. prioteloides Mader, 1942. Different from any other Mycotretus with spots, the spots of the “tiger” Mycotretus are numerous and are not bilaterally symmetrical in pattern. Here, new geographical records, diagnoses and redescriptions are provided for M. tigrinus, M. centralis, M. tigrinoides, M. tigripennis and M. prioteloides, including the first descriptions of their male and female terminalia. Lectotypes are designated for M. multimaculatus, M. centralis, and M. leopardus. Mycotretus multimaculatus and M. tigrinus pardalis Crotch, 1876 are proposed as new junior synonyms of M. tigrinus. Additionally, the authorship of the name M. leopardus is attributed to Crotch, 1876, because he was the first author to provide a description for that taxon, and the synonymy of M. leopardus and M. conspersus (Germar, 1824) with M. tigrinus (Olivier, 1792) is confirmed.


Introduction
The Neotropical Mycotretus Lacordaire, 1842 is one of the largest genera in the family Erotylidae, encompassing more than 200 described species widespread in the Neotropical region [1][2][3]. The genus is taxonomically problematic as most species are known only from older descriptions [1,4,5], information about male and female terminalia is scarce [3,6,7], and no taxonomic revision has been provided to date. Data on host fungi of Mycotretus are scarce and records are too few to discuss host fungus specialization. Most other Erotylinae species of Mycotretus feed on basidiomycete fungi, with host records in the families Pleurotaceae, Polyporaceae and Mycenaceae [3]. There are records of two different species of Mycotretus co-occurring in the same host fungus, for instance in the case of M. chilensis Crotch, 1876 andM. trifasciatus Guérin, 1956 co-occurring in the fungi Mycena sp. (Mycenaceae) and Lentinus brumalis (Polyporaceae) [3].
Redescription. Length (in mm) = 4.71-8.26 (6.87 ± 0.94, n = 23). Body elongate, slightly oval, widest at the anterior third of elytra, TL/EW = 1.57-1.80 (1.70 ± 0.05), glabrous and glossy, dorsal and ventral coloration homogeneously yellowish or reddish-brown . Mouthparts with same background color as body, mandibles apex blackish and with two teeth; mentum plate pentagonal, with strongly sclerotized margin; antennae yellowish or reddish-brown, last antennomeres blackish. Scutellar shield yellowish, reddish-brown or blackish, glabrous and bearing few punctures. Dorsal coloration: head lacking or, usually, with one to four asymmetrical subcircular black spots (Figure 1C,I,arrow); pronotum with several circular and subcircular black spots ( Figure 1A,C-L), extremely variable in size and number (usually more than ten), and asymmetrically distributed in all examined specimens (except for the specimen from Río Toro, Peru with more symmetrical pronotal spots). Elytral coloration similar to that of pronotum, with several circular and, usually, free and sparsely distributed spots (Figure 1A,.  Male terminalia. (Figure 2A-F). Penis (Figure 2A, pen) slightly elongate and curved; basal portion with a short sclerotized projection linked to apophyses; internal sac with well-developed and slightly elongated flagellum (Figure 2A, fla), 0.7 × the length of penis (n = 3), with slight sinuosity and a membranous portion between the virga and the head of the flagellum ( Figure 2B-D, mp), head of flagellum  sclerotized and elongated, with arcuate sclerotization posteriorly black arrow) and inflection at the basal half of the lateral edges. Inner contours slightly separated; anterior edge with outer sclerotization, more or less prominent and, in some individuals, forming two outer, narrowed and lateral tips ( Figure 2C, red arrows). Apophyses (Figure 2A, apo) 1.12 × as long as penis (n = 2). Tegmen sclerotized (Figure 2E); parameres reduced and sclerotized, with densely pubescent outgrowths, slightly dilated, narrowed and acute at apex (Figure 2E,arrow). Tergite VIII, sclerotized with sparsely distributed bristles and sternite VIII slightly sclerotized. Laterotergite IX sclerotized, posteriorly elongated and pubescent, outer contours angulated (Figure 2F,terg IX); anteroventral edge with paired and subparallel lateral struts, connected at its anterior tip by small Insects 2018, 9, 168 6 of 22 transverse, slightly sclerotized sclerite (Figure 2F,arrow). Posterior edge of sternite IX, sclerotized, undivided, outer contour rounded; anteriorly membranous. Tergite X, sclerotized, anterior edge with sparsely distributed bristles.   (Olivier, 1792 Diagnosis. Dorsal coloration with several circular and subcircular black spots, extremely variable in size and number and asymmetrically distributed. Penile flagellum slightly elongated (approximately 0.7 × the length of penis), slightly sinuous and with a membranous portion between its virga and head. Head of flagellum sclerotized and elongated, with an arcuate sclerotization posteriorly and an inflection at the basal half of the lateral edges. Inner contours slightly separated; anterior edge with outer sclerotization, more or less prominent and, sometimes, forming two outer, narrowed and lateral tips.
Redescription. Length (in mm) = 4.71-8.26 (6.87 ± 0.94, n = 23). Body elongate, slightly oval, widest at the anterior third of elytra, TL/EW = 1.57-1.80 (1.70 ± 0.05), glabrous and glossy, dorsal and ventral coloration homogeneously yellowish or reddish-brown ( Figure 1A-L). Mouthparts with same background color as body, mandibles apex blackish and with two teeth; mentum plate pentagonal, with strongly sclerotized margin; antennae yellowish or reddish-brown, last antennomeres blackish. Scutellar shield yellowish, reddish-brown or blackish, glabrous and bearing few punctures. Dorsal coloration: head lacking or, usually, with one to four asymmetrical subcircular black spots ( Figure 1C,I, arrow); pronotum with several circular and subcircular black spots ( Figure 1A,C-L), extremely variable in size and number (usually more than ten), and asymmetrically distributed in all examined specimens (except for the specimen from Río Toro, Peru with more symmetrical pronotal spots). Elytral coloration similar to that of pronotum, with several circular and, usually, free and sparsely distributed spots ( Figure 1A, C-L).

Mycotretus centralis
three large basal spots (medial one resembling the fusion of the two smallest spots, e.g., Figure 4I, arrow) or with four apparent spots (in this case, medial spots not completely fused, e.g., Figure 4H, arrow); four spots on disc; two or four anterior spots (in the last case, two medial spots bigger than outer ones, Figure 4C, white arrow). In some individuals, spots connected to lateral pronotal edges (Figure 4E,arrow). Elytral coloration with several black, circular and free spots, sparsely distributed. In some individuals, there are elongated spots on each elytron, resembling the fusion of two or three spots, especially on humeral angles. On the disc, somewhat transverse spots can be present (Figure 4L,arrow).    Diagnosis. Pronotum with black, free and subcircular spots, symmetrically and transversely arranged. Penile flagellum well-developed and slightly elongated, approximately 0.95 × the length of the penis, with a shallow sinuosity and without a membranous portion between the virga and head; in dorsal view, flagellum medially enlarged and slightly sclerotized and, posteriorly, at flagellum head and virga connection, strongly sclerotized. Head of flagellum sclerotized, U-shaped, each branch ending in a blunt and narrowed tip, or forming a shallow, small and narrow denticle at the outer apical edge.
Redescription. Length (in mm) = 5.07-6.89 (6.13 ± 0.60, n = 9). Body elongate, slightly oval, widest at anterior third of elytra, TL/EW = 1.60-1.77 (1.69 ± 0.06), glabrous and glossy, dorsal and ventral coloration homogeneously yellowish or reddish-brown ( Figure 4A-L). Mouthparts of same background color as body, mandible apices blackish and with two teeth; mentum plate pentagonal, with strongly sclerotized margin; antennae yellowish or reddish-brown, last antennomeres blackish. Scutellar shield yellowish, reddish-brown or blackish, glabrous and bearing few punctures. Dorsal coloration: head with one large and subcircular black spot on disc, Figure 4C,G, arrow (specimens from Guatemala with one or two black spots, small, free and close to major spot on disc); pronotum with black, free and subcircular spots (Figure 4) symmetrically and transversely arranged, as follows: three large basal spots (medial one resembling the fusion of the two smallest spots, e.g., Figure 4I, arrow) or with four apparent spots (in this case, medial spots not completely fused, e.g., Figure 4H, arrow); four spots on disc; two or four anterior spots (in the last case, two medial spots bigger than outer ones, Figure 4C, white arrow). In some individuals, spots connected to lateral pronotal edges (Figure 4E,arrow). Elytral coloration with several black, circular and free spots, sparsely distributed. In some individuals, there are elongated spots on each elytron, resembling the fusion of two or three spots, especially on humeral angles. On the disc, somewhat transverse spots can be present ( Figure 4L, arrow).  Figure 5D, red arrow) or, forming a shallow, small and narrow denticle at the outer apical edge ( Figure 5C, red arrow). Apophyses ( Figure 5A, apo) 1.2 × as long as penis (n = 3). Tegmen sclerotized ( Figure 5E); parameres reduced and sclerotized, with densely pubescent outgrowths, slightly dilated, narrowed and acute at apex (Figure 5E,arrow). Tergite VIII, sclerotized with sparsely distributed bristles and sternite VIII, slightly sclerotized. Laterotergite IX sclerotized ( Figure 5F, terg IX), posteriorly elongated and pubescent, outer contours angulated; anteroventral edge with paired and subparallel lateral struts, connected at its anterior tip, by a small, transverse and slightly sclerotized sclerite ( Figure 5F, arrow). Posterior edge of sternite IX, sclerotized, undivided, outer contour rounded; anteriorly membranous. Tergite X, sclerotized, anterior edge with sparsely distributed bristles.
Distribution. North and Central America, South and Southeast Brazil ( Figure 6).

Remarks.
(1) Mycotretus centralis has a disjunct geographical distribution ( Figure 6). See Discussion. (2) The flagellum head of the dissected Brazilian M. centralis ( Figure 5C-D) is more sclerotized and thicker than a specimen from Guatemala ( Figure 5B). (3) Interestingly, based on the pronotal color pattern of M. centralis described here, the specimen figured by Gorham as an example of M. tigrinus (see Gorham [1], Tab. III. Figure 9) is probably M. centralis. (4) A female from Derrubadas (RS, Brazil) seems to have the usual pronotal coloration of M. centralis. However, as the specimen may be a teneral, we considered it a doubtful identification.

Diagnosis.
Posterior and anterior edge of pronotum with a black, shallow and transverse mark, from which two lateral tooth-like spots arise, sometimes with a medial elongated spot; subcircular pronotal spots can be present laterally or on the disc. Elytral coloration with several black, free, subcircular or longitudinal spots, sparsely distributed (some of which are apparently fused). Penile flagellum well-developed and slightly elongated, approximately 1.34 × the length of the penis, anteriorly arcuate and with a shallow desclerotization posteriorly (absent in M. tigrinoides). Flagellum of M. tigripennis dorsally broader than that of M. tigrinoides. Head of flagellum sclerotized and subpentagonal, with outer anterior contours forming an acute angle.
Redescription. Length (in mm) = 4.52-6.25 (5.52 ± 0.49, n = 17). Body elongate, widest at the anterior third of elytra, TL/EW = 1.76-1.86 (1.81 ± 0.02), glabrous and glossy; dorsal and ventral coloration ( Figure 7G-L) homogeneously yellowish or reddish-brown; mouthparts and first antennomeres yellowish to reddish-brown; legs yellowish to reddish-brown, with coxae and tibiae partially blackish in some individuals; mandible apices partially black and last antennomeres blackish; mentum plate pentagonal, with a strongly sclerotized margin. Venter usually black with subcircular spots. Scutellar shield blackish, glabrous and bearing few punctures. Dorsal coloration: head with no spots or with one large and subcircular black spot on the disc ( Figure 7I, arrow); posterior and anterior edge of pronotum with black, shallow and transverse marks, from which two lateral tooth-like spots arise ( Figure 7I, K, small arrows), sometimes with in between elongated and medial spots (Figure 7G,arrow); sometimes with subcircular pronotal spots laterally or on the disc. Elytral coloration with several black, free, subcircular or longitudinal spots, sparsely distributed (some apparently fused).
Remarks. See the above remarks of M. tigrinoides concerning the identification of examined specimens of M. tigripennis. The specimens identified here as M. tigripennis (from Rio de Janeiro, Brazil) are far away from the type locality (Santa Inés, Ecuador) and we thought that it would be a new species at first. Although that remains a possibility, until other populations are studied, we prefer to consider these Brazilian specimens as intraspecific variation of M. tigripennis.