Mannomicrus Yoder

Yoder, Matthew, 2007, Mannomicrus (Hymenoptera: Diapriidae), a new genus of myrmecophilic diapriid, with a digital version of Masner and García's (2002) key to New World Diapriinae and an illustration of digital description and key markup using an ontology, Zootaxa 1439, pp. 47-55 : 48-53

Mannomicrus Yoder , new genus

Type species: Hemilexis jessei Mann, 1914 .

Hemilexis jessei Mann, 1914 . Original description. Illustrated. Biology. Hemilexis jessei var. minor Mann, 1914 .

Entomacis jessei: Johnson, 1992 . Cataloged.

Entomacis jessei var. minor: Johnson, 1992 . Cataloged.

Hemilexis jessei: Yoder, 2004 . Considered as Spilomicrini, incertae sedis.

Type material: The holotype (deposited at MCZC) of H. jessei is in good though somewhat dirty condition, with the left antenna missing segments past the 3rd and the right antenna missing segments past the 11th.

Etymology. A combination of " Mann ", in reference to the describer, and "micrus" implying relationship to other spilomicrines. Note that Mann (1914) described H. jessei and dedicated it to his "…small collecting companion, Master Jesse Van Law.", it is unclear as to whether Van Law or Mann collected the actual type series.

Classification. Mannomicrus is easily recognized as a member of the Spilomicrini by the 13 segmented antennae and characteristic venation (marginal vein relatively long, submarginal clearly separated from anterior margin of forewing). For a further diagnosis of the tribe see Masner and García (2002).

Diagnosis. Most similar to species of the genera Spilomicrus and Bruchopria , from which it differs by the characters listed in Table 1 . Mannomicrus can be identified by modifying the key of Masner and García (2002) as follows (see also the on-line key and color images available at http://www.diapriid.org):

28 (27). Anterior scutellar pit distinctly bifoveate; basal vein in forewing often present (nebulous); frons unarmed; Nearctic and Neotropical ................................ Spilomicrus Westwood [male/female] (part)

- Anterior scutellar pit unifoveate, at most with very slight medial ridge and/or some irregularly spaced longitudinal carinae, or pit absent; basal vein in forewing absent or at most spectral to very slightly sclerotized; frons armed or unarmed...................................................................................28a

28a(28). Frons with two sharp points and transverse ledge; body not completely covered with short appressed setae; basal vein in forewing absent; South America [m] (part) ............................ Mitropria Ogloblin

- Frons without two sharp points and transverse ledge (fig. 1, 2); body completely covered with short appressed setae; basal vein in forewing at most spectral or slightly sclerotized; Mexico [mf] ........... ......................................................................................................... Mannomicrus Yoder New Genus Description. Female (males unknown), length 2.1–3.0mm, mean=2.6.

Head. Width: 0.46–0.56mm, mean=0.54; height: 0.46–0.61mm, mean=0.66; length: 0.46–0.55mm, mean=0.52 ( Fig. 3 ); mandible broad, bidentate, with two teeth of subequal length at apex with few scattered erect setae medially and towards base; clypeal ledge reduced, separated from clypeus by narrow groove; clypeus trapezoidal, bearing 4–5 setigerous punctures laterally, setae erect and long; supraclypeal face flat, with all but medial strip densely covered with short, appressed setae, interspersed with few scattered erect longer setae; malar sulcus absent; eye asetose; ommatidia small, surrounded by glabrous patch; dorsal head (frons and post-ocellar vertex), except for small patch surrounding ocellar triangle, densely covered with short appressed setae; posteroventral gena with thick patch of setae, these setae being slightly longer than those appressed on remainder of head; longer erect setae absent on dorsal head and gena; occipital carina complete, short and blade-like; maxillary (3? segmented) and labial (2? segmented) palps very reduced; hypostomal carina short, sharply defined.

Antenna. ( Fig. 6 ) Scape thickening towards apex, apex with short but well-developed flanges laterally and slight depression ventrally; pedicel reduced, not much larger than A3; A3 slightly longer than or subequal to A4; A4–A7 subequal, cylindrical; A8 broader than A7, following segments subequal; A8–A13 with MGS brush ( Yoder 2004), only very slightly flattened ventrally; antennomeres densely covered throughout with short, fine, semi-appressed setae (sensilla); 1–3 erect uniporous? sensilla present along dorsal and ventral surfaces of A8–A13.

Mesosoma. Width: 0.50–0.65mm, mean=0.52; height: 0.48–0.63mm, mean=0.57; length: 0.85–1.17mm, mean=1.05 ( Figs. 4–5, 7 ); all of mesosoma, except for small subcircular patch on lateral pronotum and medial strip of dorsal mesoscutum and scutellar disc, densely covered with short, appressed setae, setae of metathorax particularly dense; pro- and mesosoma without any longer semi-erect to erect setae; pronotum in dorsal view ( Fig. 5 ) broadly visible to near axilla, area anterior to anterior-most mesoscutum unmodified, laterally sub-triangular, only slightly depressed near propleural suture; notauli absent or indicated as fine creases across mesoscutum, mesoscutum where notauli usually located bare ( Fig. 5 ); anteromedian and parapsidal lines absent or very slightly indicated as shallow depressions; humeral and suprahumeral sulci absent; mesopleuron more or less flat, with few elongate narrow grooves in upper-posterior corner; epicnemial pit very reduced, slit like; median oblique line absent; anterior scutellar pit present, shallow, transversely elongate, with 2–4 longitudinal carinae at its base; posterior junction of axillae to scutellar disc finely carinate; scutellar disc with lateral edges irregularly carinate, lateral-most edge sharply carinate, posterior margin lined with short, irregular scrobiculae; dorsellum with medial keel and lateral keels absent; axillar depression reduced, not deeply impressed; metapleuron more or less flat, depressed slightly just above hind coxa; outer metanotal process subtriangular, glabrous; propodeum somewhat flattened, carina forming posterior margin very well-developed, sub-horizontal, in dorsal view completely obscuring nuchal area, nucha, and most of petiolar flange; median propodeal keel short ( Fig. 5 ); all legs relatively uniform in form and as follows- coxa small; trochanter without distinct invagination near apex; femur massive, thickened all but basally, slightly flattened and glabrous ventrally, particularly near apex; tibia with narrow elongate base, widening evenly towards apex; tarsal segment one the longest, two to four subequal, short, five longer ( Fig. 7 ); pretarsal claws very well-developed, crescent shaped, sharply pointed at apex.

Wings. ( Fig. 9 ) Forewing submarginal vein separated from anterior margin by clear gap, marginal vein elongate, clearly longer than very short stigmal vein, remaining venation absent to spectral; forewing marginal microtrichia very short (anterior margin) to completely absent (posterior margin); hind wing with only slightly sclerotized submarginal vein, remaining venation absent, with marginal microtrichia developed similarly to forewing.

Metasoma. ( Fig. 8 ) Petiole elongate, subcylindrical, with no prominent carinae except near petiolar flange and along ventrolateral most margin, completely densely covered with short appressed to semi-erect setae and with much longer, erect setae on lateral surface; gaster formed by 6 tergites and 5 sternites, with no short appressed setae except for small irregular patch on basoventral S2, with longer, erect setae more or less evenly spaced throughout; ovipositor tip sharp, in some specimens extruded prominently, terminalia otherwise hidden.

Color. Legs, scape, and pedicel light yellow-brown; remaining body brown; anterior and ventral pronotum lighter in some; smaller individuals lighter color overall.

Va r ia ti o n. Mann (1914) was probably led to describe Hemelexis jessei var. minor based on the lighter color andslightly smaller size of the individuals in question. Smaller individuals (including, but not limited to the two specimens labeled Hemelexis jessei var. minor ) are generally lighter colored throughout, the pronotum more exposed in dorsal view and the setae appear narrower and slightly lighter. The observed variation is much less than seen in other diapriid species, particularly those that are gregarious parasites, and it is clear that the specimens represent a single species.

Biology. The type series is associated with several ant specimens that Mann (1914) collected. Mann (1914) states these ants to be Formica subcyanea Wheeler. This identification is confirmed by a determination attached to the specimen made by T.P. Nuhn 2001, and by a subsequent determination made by myself. Mann (1914) noted that only one or two wasps were present in each colony and that they moved slowly (and freely) among the ants. Masner and García (2002) observed that many specimens of Bruchopria have their wings torn or completely removed (likely by ants); this was also the case of most of the specimens of M. jessei examined. In some individuals the ovipositor (not sheath) is extruded to a degree not typically seen in other genera of Diapriinae , and its tip appears quite sharp. The form of the ovipositor would seem to indicate that M. jessei is endo- rather than ectoparasitic, though this remains to be proven.

Distribution. All labels bear the same information, "GuerreroMill. | Hidalgo, Mexico | W.M. Mann.", though some are alternately spelled "Guerrer e oMill". Mann (1914) notes the locality as "Guerrero Mill, located below Real del Monte, at the Hacienda de Velasco". Guerrero Mill, Mineral del Monte, is at 20.15667N, - 98.66W, elevation 2600m, in the state of Hidalgo.

Remarks. While Mannomicrus jessei clearly has affinities to species of Spilomicrus extending the generic concept of Spilomicrus , a very specious genus (> 160 species), to incorporate M. jessei is undesirable for several reasons: 1) it would greatly weaken the differential diagnosis of Spilomicrus by allowing for an exception to the otherwise uniform characters of form of the anterior scutellar pit and absence of short, appressed pilosity; and 2) it would overlook differences in biology, as species of Spilomicrus , with the possible exception of S. myrmecophilus , are not known to be myrmecophilic. Based on the description of Nixon (1947) S. myrmecophilus shares several similarities with M. jessei : 1) the anterior scutellar pit is not paired, being highly reduced; 2) the pronotum is broadly visible in dorsal view; and 3) the ovipositor is long and sharply pointed. However, S. myrmecophilus does not exhibit short appressed setae as seen in M. jessei . Similar problems with the generic placement of S. myrmecophilus exist. Nixon (1947) notes: "I have placed this species in Spilomicrus Westwood for reasons of convenience. It cannot be said rightly to belong here. …". As gross morphological convergence is frequently associated with myrmecophily, it will require further study, perhaps molecular, to determine the precise relationships of M. jessei and S. myrmecophilus to other spilomicrines. The disparate distribution of the two species ( Mexico, Mauritius) suggests that similarities in morphology may be due to convergence.

The generic description provided here is relatively specific with respect to setal characteristics. We expect that additional species in this genus, if discovered, may have some variation with respect to the pilosity patterns noted here.

Figures

FIGURE 1 – 3. Mannomicrus jessei (Mann), female; 1 - habitus, lateral; 2 - habitus, dorsal; 3 - head, anterior.

FIGURE 4 – 9. Mannomicrus jessei (Mann), female; 4 - scutellum, propodeum, petiole and anterior T 2, dorsal view; 5 - mesosoma, dorsal view, note that the anterior scutellar pit illustrated here is considered to be unifoveate, see digital key for true bifoveate state; 6 - antennal, lateral view; 7 - hind tarsus, note well-developed tarsal claws; 8 - posterior metasoma, dorsal view; 9 - forewing, note absence of long microtrichia along margin; inset- form of submariginal (= radial) vein junction to anterior margin of forewing.

Tables

TABLE 1. Characters diagnosing Mannomicrus jessei (Mann) from species of Spilomicrus and Bruchopria.

Character / Taxon	Spilomicrus spp.	M. jessei (Mann)	Bruchopria spp. sensu Mas- ner and García (2002)
anterior scutellar pits	2- prominent clearly sepa- rated pits, pits infrequently with scattered carinae	1- carinate throughout, medial most carina some- times enlarged, but never to the degree found in species of Spilomicrus	0- no pit present
posterodorsal pronotum	unmodified, not promi- nently visible in dorsal view	flat, prominently visible in dorsal view	elevated (dentate), prominently visible in dorsal view
petiole	elongate cylindrical	elongate cylindrical	short, transverse
setae of metasoma/ propodeum	varied, but usually dense and long and never uni- form, dense and short	dense and short	dense and short