Lathrobium pacei Piva, 1995

Staniec, Bernard & Bordoni, Arnaldo, 2022, Comparative larval ultramorphology of three endemic Lathrobium (Glyptomerus) species (Coleoptera, Staphylinidae, Paederinae) from the Eastern Alps in Italy, Zootaxa 5175 (2), pp. 206-230 : 221-224

Lathrobium pacei Piva, 1995

Body elongate, moderately flattened, relatively slightly sclerotized; head (1.2×) wider than pronotum ( Figs 3, 6, 9 ). Colour: head yellow; mandibles brown; pronotum pale yellow with barely visible darker posterior edge; antennae, maxillae, labium, legs, urogomphi and remaining parts of body colourless. Setae as in Fig. 89 and similar to those illustrated in Figs 86–88, 90 .

Head ( Figs 12 , 17 ): semi-triangular in outline, widening distinctly from neck to anterior margin, broadest between stemmata, width ratio of neck and head between stemmata = 1:3.6; moderately flattened dorso-ventrally, about 1.2× as wide (between stemmata) as long; dorsal ecdysial lines (Es) bifurcate at about 0.4× length of head measured from anterior margin of nasale; stemmata present, ordered as in Fig. 14 . Epicranial part (E) ( Fig. 12 ) with 6 pairs of long setae (coded: Ed1–3, El1, Em2–3), a pair of glands (Gl) and a pair of pores (C1). Chaetotaxy of ventral side with 8 setae (2[V1, Vl1-3]) and 2 pairs of pores 2(C1–2). Apotome (Ap) not reaching tentorial pits (Tp) ( Figs 17, 20 ). Gular region as in Fig. 23 . Functional position of nasale (Na), antennae (At), mandibles (Md), maxillae (Mx), maxillary palps (Mp), labial palps (Lp) and ligula (Lg) as in Fig. 91 . Antenna ( Figs 28, 29 ): length ratios of articles I–IV = 1:3.9:3.8:2.0. Article I almost 1.2× as wide as long; article II 4.3× as long as wide, with 4 pores; article III 4.7× as long as wide, with 3 macro setae, one strongly elongate, almost dagger-shaped sensory appendage (Sa), 6.2× as long as wide, growing from basal protuberance, 3 solenidia (IIIS1–3) of different lengths, and 1 pore ( Figs 28, 29 ); article IV moderately elongate, gradually widening to apex, 4.4× as long as wide, solenidia apically (IVS1–4) as in Fig. 29 ; length ratio of article IV and Sa: 1.1:1 ( Fig. 29 ). Anterior margin of nasale with 9 teeth ( Figs 34, 35 )—one big median (Mt) rounded anteriorly ( Fig. 35 ) and serrate, a pair of high paramedian (Pmt) and three pairs of lateral ones (Lt1–3) ( Figs 34 , 93); Lt1 tiny, almost invisible, Lt3 indistinctly pointing outwards, the others forwards, height ratio Mt and Pmt = 1:1.2; width ratio Mt and Pmt = 1.1:1; setae of Ps1–4 nodular or peg-like ( Figs 34 , 96). Adoral surface of nasale (epipharynx) ( Fig. 40 ) with two transverse rows: one with over 100 long cuticular processes (Acp) along anterior margin of buccal cavity (Bc), the other with about 40 short cuticular processes (Pcp) along posterior margin of buccal cavity; pharynx (Ph) with a pair of sensilla (Sm); anterior region with distinct, reticulate microstructure ( Fig. 41 ).

Mandible ( Figs 46, 46A, 46B , 100, 101 ) falciform, strongly elongate and narrow, moderately elongate and narrow, inner margin without any teeth; base with a group of cuticular processes ( Fig. 98 ). Maxilla ( Figs 50, 54 ): length ratio of cardo (Cd) and stipes (Stp) = 1:1.3; cardo 1.2× as long as wide; stipes 2.2× as long as wide; mala (Ma) elongate, tapering moderately to apex, 4.6× as long as wide, with 6 long setae, 1 tiny and 1 robust apical sensory appendage, and 2 pores basally ( Fig. 54 ). Maxillary palp (Pm): ratios of articles I–III = 1:1.5:2.5; article I slightly shorter than mala, 3.0× as long as wide with 2 pores apically; article II 5.1× as long as wide, widening moderately to apex, seta 1 longer than seta 2, seta 2 located closer to top than to base; article III 11.8× as long as wide with 1 digitiform sensory appendage basally and a bunch of a few elongate sensory appendages apically ( Fig. 50 ).

Labium ( Figs 57 ): dorsal side of labium (hypopharynx) slightly sclerotized laterally, central and basal portion membranous, microtrichia forming relatively wide band just reaching posterior margin ( Fig. 57 ). Ventral side of labium with trapezoidal prementum (Pmnt), in outline 1.2× wider anteriorly than at base ( Fig. 60 ); ligula (Lg) with long thick microtrichia, about 2.6× as long as wide, clearly separated from Pmnt by distinctly sclerotized transversal strip (St); length ratio Lg and article I of labial palp (Lp): 1:1.3. Labial palps ( Fig. 63 ): article I 4.7× as long as wide, more or less straight; article II slightly arcuate, 5.7× as long as wide, with a bunch of a few sensory appendages apically and 1 pore near apex; length ratio of articles I and II = 1.6:1.

Thorax. Fore leg ( Fig. 71 ): length ratios of Cx, Tr, Fe, Tb, Tu = 5.3:1.9:5.9:5.1:1; Cx 3.6× as long as wide; Tr 2.7× as long as wide; Fe 7.2× as long as wide with about 45 spinose setae (about 20 tiny dorsally) and a few pores; Tb 13.0× as long as wide with about 30 setae (27 long); apical section of Tu slightly curved, relatively long, 6.5× as long as wide, setae (coded 1, 2) unequal in length, seta 1 2.1× longer than seta 2 ( Fig. 72 ). Mid leg (only differences compared to the first pair) ( Fig. 73 ): length ratios of Cx, Tr, Fe, Tb, Tu = 5.1:1.8:5.6:6.2:1; Cx 2.9× as long as wide; Tr 2.5× as long as wide with 8 setae and a few pores; Fe 7.6× as long as wide with about 45 spinose setae (about 20 tiny dorsally); Tb 13.9× as long as wide with about 30 setae (27 long); apical section of Tu slightly curved, relatively long, 6.7× as long as wide, setae (coded 1, 2) unequal in length, seta 1 1.9× longer than seta 2 ( Fig. 74 ). Sternum with chaetotaxy as in Fig. 78.

L. alzonai , L. freyi and L. pacei the following chaetotaxy are shared: pronotum with 22 setae - 2(A1–2, L1, L3, L6, L10, Da2, Db1–2, P2, P4), 16 pores -2(Ap1–2, Dp1–2,Pp1–4) ( Fig 75 ); tergite III (the same as in the case of segment II) with 20 coded setae - 2(A1–4, Da2, Db2, L6, L10, P2, P4), 20 tiny uncoded setae and 6 pores - 2(Ap1–2, Pp1) ( Fig. 79 ); abdominal tergites I-VIII each with 10 coded setae - 2(A1, A3–4, P2, P4), 8–12 tiny uncoded setae, 0–4 pores - 2(Pp1, Pp2) and a pair of tergal galds (Tg)—in abdominal segments I and VIII only ( Figs 79–81 ); dorsal side of abdominal segment X with 6 long, 6 tiny setae and a pair pores ( Fig. 81 ); abdominal sternite I with 10 tiny setae - 2(A3, A4, Da2, Db2, P3) and abdominal sternites II–IX with 24 setae ( Figs 82, 83 ); ventral side of abdominal segment X with 20–22 setae (10 long); segment I of urogomphus (Ug) with 15 setae (7 long), segment II with 2 setae (1 long apically); length ratio of segments I, II, and apical seta of Ug: 6.1:1:2.4 ( L. alzonai ) and 4.1:1:2.6 ( L. pacei ) ( Figs 84, 85 ). The region between pro- and mesothorax, and abdominal segments I–VIII, each with a pair of circular spiracle (Sp) ( Fig. 108 ).

Figures

FIGURES 1-9. Mature larva, habitus. 1, 4, 7, Lathrobium alzonai; 2, 5, 8, L. L. freyi; 3, 6, 9, L. pacei.

FIGURES 86-96. Mature larva of L. alzonai (86, 88, 90, 92, 94, 95), L. freyi (87, 91, 96) and L. pacei (89, 93). 86, seta of tibia; 87-90, abdominal setae; 91, head in frontal aspect; 92, 93, median tooth; 94-96, region of paramedian tooth. Abbreviations: At—antenna, Ch—channels, Gp—glandular pit, Lg—ligula, Lp—labial palp, Ma—mala, Md—mandible, Mp—maxillary palp, Mt—median tooth, Na—nasale; Pmt—paramedian tooth, Ps—peg seta.

FIGURES 10-14. Mature larva of L. alzonai (10, 13), L. freyi (11) and L. pacei (12, 14). 10-12, head in dorsal aspect; 13, microstructure of head near dorsal ecdysial suture; 14, region of stemmata. Abbreviations: At—antenna, C—epicranial campaniform sensilla, E—epicranial part, Es—dorsal ecdysial suture; Ed—epicranialodorsal seta, El—epicranialolateral seta, Em—epicranialomarginal seta, Gl—gland, Gp—glandular pit, Md—mandible, P—posterior part/posterior seta, Trb— trichobothrium.

FIGURES 15-23. Mature larva of L. alzonai (15, 18, 21), L. freyi (16, 19, 22) and L. pacei (17, 20, 23). 15-17, half of head in ventral aspect; 18-20, apotome and tentorial region;21-23, gular region.Abbreviations:Ap—apotome,C—epicranial campaniform sensilla; Tp—tentorial pit, Trb—trichobothrium, V—ventral seta, Ves—ventral ecdysial suture, Vl—ventrolateral seta.

FIGURES 24-35. Mature larva of L. alzonai (24, 25 30, 31), L. freyi (26, 27, 32, 33) and L. pacei (28, 29, 34, 35). 24-29, left antenna (24, 26, 28) and apical section (25, 27, 29) in dorsal aspect; 30-35, anterior margin of nasale (30, 32, 34) and region of median and paramedian teeth (31, 33, 35) in dorsal aspect; Abbreviations: Lt—lateral teeth, Pmt—paramedian tooth, Ps—peg seta, Mt—median tooth, I-IV—antennal and maxillary palp articles, Sa—sensory appendage, So—solenidia.

FIGURES 36-46. Mature larva of L. alzonai (36, 37, 42-44), L. freyi (38, 39, 45) and L. pacei (40, 41, 45, 46, 46A, 46B). 36-41, epipharynx and microstructure (37, 39, 41); 42-46, right (42, 44-46) and left (43) mandible with distal portion (43, 44, 46B) and region of seta L1 (46A). Abbreviations: Acp—anterior cuticular processes, Bc—buccal cavity, Ch—channels, L1, L2—code of mandibular setae, Mt—median tooth, Pcp—posterior cuticular processes, Ph—pharynx, Pmt—paramedian tooth, Ps1—peg seta, Sm—sensillum.

FIGURES 97-108. Mature larva of L. alzonai (97, 99, 102-105, 107, 108), L. freyi (106) and L. pacei (98, 100, 101). 97, 98, base of mandible with microstructure; 99, 100, mandible in dorsal (99) and ventral (100) aspect; 101, micro seta (L1) of mandible; 102, mala; 103, apical section of mala; 104, apical section of stipes in dorsal aspect; 105, apical section of maxillary palp; 106, ligula in dorsal aspect; 107, microstructure of anterior region of mesonotum; 108, abdominal spiracle of pair VI. Abbreviations: Lg—ligula, Ma—mala, Mi—microtrichia, Mp—maxillary palp, Sp—spiracle, St—stipes, L1, L2—setae of mandible.

FIGURES 47-54. Mature larva of L. alzonai (47, 47A, 48, 51, 52), L. freyi (49, 53) and L. pacei (50, 54). 47-54, right maxilla with stipes (48), microstructure near trichobothrium (51) and region of mala (52-54) in ventral aspect. Abbreviations: Cd— cardo, Pf—palpifer, Ma—mala, I-III—antennal and maxillary palp articles, St—stipes, Trb—trichobothrium, 1, 2—setae of maxillary palp.

FIGURES 55-63. Mature larva of L. alzonai (55, 58, 61), L. freyi (56, 59, 62) and L. pacei (57, 60, 63). 55-57, hypopharynx in dorsal aspect; 58-60, labium in ventral aspect; 61-63, left side of labial palp in ventral aspect. Abbreviations: Lg—ligula, Lp—labial palp, Pmnt—prementum.

FIGURES 64-74. Mature larva of L. alzonai (64-67), L. freyi (68-70) and L. pacei (71-74). 64, 68, 71, right fore leg in anterior aspect; 65, 67, 70, 72, 74, tarsungulus of fore (65, 72) and middle (67, 70, 74) pair of legs.Abbreviations: Cx—coxa, Fe—femur, Tb—tibia, Tr—trochanter, Ts—tarsungulus.

FIGURES 75-81. Mature larva of L. pacei (75, 78, 79-81), L. freyi (76) and L. alzonai (77, 77A). 75, pronotum; 76-78, prothorax and microstructure of lateral region (77A); 79, thoracic tergite III and abdominal tergite I; 80, abdominal tergite II; 81, abdominal segments IX and X in dorsal view. Abbreviations: A—anterior seta, Ap—posterior pore, D—discal setae of rows a and b, L—lateral seta, P—posterior seta, Pr—presternum, Te—tergite, Tg—tergal gland, Sp—spiracle, Stp—sternum, Ug—urogomphus.

FIGURES 82-85. Mature larva of L. alzonai (82, 84) and L. pacei (83, 85). 82, abdominal sternite I-III; 83, abdominal segments VII-X in ventral aspect; 84, abdominal segments IX and X and urogomphus in lateral aspect; 85, abdominal segment X and urogomphus in dorsal aspect. Abbreviations: A—anterior seta, D—discal setae of rows a and b, L—lateral seta, P—posterior seta, St—sternite, Te—tergite, Ug—urogomphus, I, II-…abdominal segments, sternites or segments of urogomphus.