Systematics of the seed beetle genus Decellebruchus Borowiec, 1987 (Coleoptera, Bruchidae).

Keys to species, descriptions, synonymy, host plants, and geographical distributions are presented for the three species in the genus Decellebruchus (Borowiec 1987); of those, Decellebruchus walker (Pic 1912) was the only species included at the time of the genus denomination, Decellebruchus atrolineatus (Pic 1921) is transferred to this genus, and Decellebruchus lunae is described as a new species. The shortest and most parsimonious phylogenetic tree for genera with pectinate antennae had a length of 33, consistency index 87, and retention index 81.

Introduction

The monotypic genus was erected by Borowiec in 1987 with the type species (Pic 1912). This species has a complicated history, starting with that was described by Walker (1859); however this was a homonym and then Pic (1912) proposed the replacement name of . Later Decelle (1975b) transferred it to , but because the unusual pectinate antennae of the species in the genus , Borowiec (1987) erected the monotypic genus for it. Another species that has been included unofficially in the latter genus is Pic, 1921; however has also PageBreaksuffered a series of generic changes through time. Finally the third species included in the genus is the new species . In order to clarify the genus it is reviewed and a hypothesis of its phylogeny is proposed.

Material and methods

Specimens. Preparation of genitalia for study followed the techniques and nomenclature described by Kingsolver (1970) and modified by Romero and Johnson (1999). For specimens the following collections were consulted: , , ; .

Colección Entomológica del Colegio de Postgraduados, Montecillo, Estado de México, México

Florida PageBreakState Collection of Arthropods, Gainesville, Fl, USA

Musee Zoologique de l’Universite de Lund, Lund University, Sweden

South African National Collection of Insects, Queenswood, South Africa

Cladistics. External morphological characters and internal characters, these latter only from male genitalia (Table 1) were used. Host plants and distribution were also considered. Taxa included in the analysis were only those bruchids with pectinate antennae (excluding the genera and because they have only few species with pectinate antennae) and all species in the genus . , a less derived genus was used as the outgroup. The data matrix is presented in Table 2. The program Hennig86 (Farris 1988) was used to generate the cladogram, although a comparative tree was obtained with Mesquite, version 3.04 (Maddison and Maddison 2015) using the same data matrix.

Table 1.

Characters used for the cladistic analysis for with pectinate antennae.

External morphology
0. Body length	8–16 mm: 0; 1.5–5.4 mm: 1
1. Eye sinus	Shallow: 0; deep: 1
2. Male antenna shape	Not pectinate: 0; pectinate 1
3. Last antennal segment	About half as long as hind tibia: 0; as long as or longer than hind tibia: 1
4. Carina media on frons	With carina: 0; without carina: 1
5.Pronotal carina	Complete: 0; no complete:1
6. Pronotum shape	Not conical, without distinctly concave sides: 0; conical with distinctly concave sides: 1
7. Pronotal disc	Without gibbosites: 0; with gibbosites: 1
8. Scutellum shape	Subsquare: 0; elongate: 1
9. Metepisternal sulcus	With sulcus:0; without sulcus: 1
10. Tenth elytral stria	Extending nearly to apex of elytron: 0; extending to half of elytron: 1
11. Elytral basal tubercles	Without tubercles: 0; with tubercles: 1
12. Pygidium articulation	Pygidium and penultimate tergum partially fused and no covered by elytra 1; Penultimate tergum no fused to pygidium and covered by elytra 2
13. Hind femur	Without carinae: 0; with one carina or obsolete carinae 1; bicarinate: 2
14. Spines on hind femur	With 10-14 spines: 0; with 1 to 3 spines: 1; without spines: 2
15. Hind tibia carinae	With complete set of carinae: 0; incomplete set of carinae: 1
16. Tuft of white setae on fore coxa	Without tuft of white setae: 0; with tuft of white setae: 1
17. Male pygidium	Reclinate 0; vertical 1
Internal morphology
18. Lateral lobes of male genitalia	Fused 0; divided 1
19. Ventral valve of male genitalia	No arcuate: 0; deeply arcuate 1
20. Shape of apical portion of median lobe of male genitalia|	No bulbous: 0; bulbous: 1
21. Basal strut of lateral lobes of male genitalia	With an obsolete or small perpendicular keel: 0; with strong perpendicular keel 1
22. Armature of internal sac of male genitalia	Only with spinules: 0; with spinules and small teeth 1
Ecological characters
23. Distribution	Worldwide 0; New world 1; Old world: 2
24. Host plants	Arecaceae: 0; Fabaceae: 1; Convolvulaceae: 2

Table 2.

Data matrix.

Taxa	Character
	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24
1. Pachymerus	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0
2. Kytorhinus	1	1	1	1	0	1	0	0	1	1	0	0	1	1	2	1	0	1	0	0	0	0	0	0	1
3. Megacerus	1	1	1	1	1	1	0	0	0	1	1	0	0	1	1	0	0	1	0	0	0	0	0	1	2
4. Callosobruchus	1	1	1	1	1	1	0	1	0	1	0	1	0	2	1	0	0	1	1	0	0	0	0	2	1
5. Conicobruchus	1	1	1	1	1	1	1	0	0	1	0	0	0	1	1	1	0	0	1	0	0	0	0	2	1
6. Rhipibruchus	1	1	1	1	1	1	0	1	0	1	0	1	0	1	1	0	0	1	1	0	0	0	0	1	1
7. Pectinibruchus	1	1	1	1	1	1	0	1	1	1	0	0	0	1	1	1	0	1	1	0	0	0	0	1	1
8. Decellebruchus atrolineatus	1	1	1	1	1	1	0	1	0	1	0	1	0	1	1	0	1	1	1	1	0	0	0	2	1
9. Decellebruchus walkeri	1	1	1	1	1	1	0	1	0	1	0	1	0	1	1	0	1	1	1	1	1	0	1	2	1
10. Decellebruchus lunae	1	1	1	1	1	1	0	1	0	1	0	1	0	1	1	0	1	1	1	1	0	1	1	2	1

Taxonomy

Borowiec

Borowiec, 1987: 149.

Description.

Male. Vestiture: Moderately dense or dense, variegated; front coxa with a wide tuft of white setae. Body oval and stout. Head: Short, strongly constricted behind eyes, postocular lobe very short; eyes bulging, deeply emarginate; frons narrow, with sharp median carina; antennae pectinate from 4th or 5th segment. Prothorax: Pronotum subconical, without lateral carina; disc convex, slightly gibbous before scutellum and with shallow median channel; prosternal process narrow, triangular, acute. Meso- and metathorax: Scutellum square, bidentate apically; elytral striae regular; striae 4 and 5 abbreviated basally by tubercle. Legs: Metacoxa densely punctate; hind femur moderately swollen, ventral carinae obsolete. Internal ventral margin with small subapical spine, often followed by two smaller spines; hind tibia straight, enlarged, with complete or incomplete set of carinae, mucro longer than lateral coronal denticle. Abdomen: More or less telescoped, fifth sternite deeply emarginated; pygidium vertical. Genitalia: PageBreakInternal sac of male genitalia lined with fine spines with or without sclerites; ventral valve deeply arcuate. Female. Similar to male, except antenna not pectinate, eyes less bulging, pygidium subvertical, last abdominal sternite not emarginated.

(Pic, 1921) comb. n.

Pic, 1921: 15,

:

:

Pic, 1931;

:

:

:

Male (Fig. 1a–b). Length (pronotum-elytra): 2.4–2.6 mm; width: 1.4–1.6 mm; maximum thoracic depth 1.5–1.7 mm. Color: Antennae with the first three segments yellowish, the rest dark or partially dark; head, prosternum, metasternum, base of meso-femur and meta-femora, and coxae dark; pronotum with two longitudinal dark bands, which may together form a dark spot; elyton variegate; pygidium with three pairs of dark spots, two apical, two median-lateral, and two basal; rest of body yellowish. Vestiture: Body with mixed yellowish and white pubescence; scutellum with whitish pubescence; fore coxa with a tuft of white setae; pygidium with yellowish and whitish pubescence forming a variegate pattern. Head: Short and broad, densely micropunctulate, frons with a strong median carina, distance between eyes 2.3.–3.3× as wide as eye width, eye cleft 0.60–0.71× its length by ocular sinus, posterior margin of eye protruding from adjacent surfaces, postocular lobe rounded and setose; distance from base of antennae to apex of labrum 0.39–0.55× as long as distance from upper limits of eyes to apex of labrum; antennomeres I–III filiform, IV subserrate, V–XI pectinate; antennomere II 2.8–3.8× as long as antennomere XI; antennomere VII 4.4–5.6× wider that long; antenna extending slightly beyond humerus. Prothorax: Subconical, without lateral carina; densely foveolate, disc convex, slightly gibbous before scutellum PageBreakPageBreakand with shallow median channel; prosternal process narrow, triangular, acute, half as long as procoxae. Meso- and metathorax: Scutellum square, bidentate apically; elytral striae regular, striae 4 and 5 abbreviated basally by tubercle, humeri raised. Legs: First protarsomere 2.0–3.0× as long as second, first mesotarsomere 1.8–2.3× as long as second, first metatarsomere 2.6–3.0× as long as second; metacoxa densely punctate; hind femur constricted basally and apically, expanded medially to about width of coxa; without external carina ventrally; internal ventral carina with small subapical acuminate spine about half as long as width of tibial base; hind tibia straight, enlarged, with only mesal and ventral carinae; tibial corona with 4 spinules, mucro 0.10–0.13× as long as first tarsomere; without sinus at base of spine; first hind tarsomere with ventrolateral glabrous longitudinal carina. Abdomen: Pygidium vertical (Fig. 2); last sternite emarginate. Genitalia: Median lobe moderately long, ventral valve triangular and deeply arcuate, internal sac with many small spines or needles, without large sclerites (Fig. 3a); lateral lobes elongate, expanded at apex, cleft about 0.53 their length; basal strut an obsolete perpendicular keel (Fig. 3b). Female (Fig. 4a–b). Length (pronotum-elytra) 2.4–2.8 mm, width: 1.5–1.7 mm, Maximum thoracic depth 1.6–1.8 mm. Similar to male except antennae serrate; distance between eyes 1.8.–2.0× as wide as eye width; pygidium subvertical; last sternite not emarginate.

Figure 1.

Male habitus of ; a dorsal view b lateral view.

Figure 2.

Male pygidium of .

Figure 3.

Male genitalia of ; a median lobe b lateral lobes.

Figure 4.

Female habitus of ; a dorsal view b lateral view.

Material examined.

NAMIBIA: Rundu, 28/V/2015, T. Chauke, , reared seed (L.), intercepted at Pretoria SAAFQIS Plant Quarantine Station, South Africa, Sample Pta. 2811 (1 ex SANC). Caprivi region, 2002, intercepted at Pretoria SAAFQIS Plant Quarantine Station, South Africa (70 ex SANC). AFRICA: Intercepted at USA, 36/XII/2003, reared seed sp. (3 ex, FSCA); Intercepted at Atlanta, USA, 10/IX/2006, reared seed L. (1 ex., FSCA). DEMOCRATIC REPUBLIC OF THE CONGO: N of Shaba Province, 28/III/1980, Whitecomb W.H., in cowpeas (1 ex., FSCA). NIGERIA: Intercepted at USA, 2/II/2004, sp. (7 ex., FSCA); Intercepted at USA, 3/II/2004, reared seed sp. (2 ex., CEAM). MEXICO: Ocolome, El Fuerte, Sinaloa, 21/I/2013, Lugo G.G.A., reared seed (L.) WALP. (190 ex., CEAM).

Host plants.

L., (L.), L. (L.) Walp., (Harv.) Maréchal & Al., (L.)Walp. (). Zacher (1952) stated that Medik. and L. are plant hosts of , however this information must be corroborated.

Distribution.

Algeria, Angola, Brazil, Burkina Faso, Cameroon, Central African Republic, Democratic Republic of the Congo, Egypt, Ethiopia, Gambia, Ghana, Jamaica, Kenya, Liberia, Mali, Mexico, Mozambique, Namibia, Niger, Nigeria, South Africa, Saudi Arabia, Senegal, Sudan, Tanzania, Uganda, United Kingdom, Yemen, Zanzibar.

Discussion.

has high economic importance, because it is a pest mainly in species in the genus . It is frequently found together with (F.). Large losses due to this insect are reported frequently in some countries of Africa, where those bruchids are endemic (Booker 1967, Germain et al. 1987, Ofuya and Credland 1996, Sanon et al. 2005).

Romero sp. n.

http://zoobank.org/4156F64D-289A-4C0E-BA2A-18A7FBD80F10

Type series.

Holotype male, allotype female and two paratypes: M. Elgon, Kenya, 20/I/1979, 1900 m, Palm T. (MZLU), one paratype same data, except 22/I/1979, 2010 m (MZLU). One paratype: Kingsburg beach, Natal, South Africa, 10/IV/1992, O’Brien C.W., L.B. O’Brien & G. Marshall (CEAM).

Male (Fig. 5a–b). Length (pronotum-elytra): 2.0–2.13 mm; width: 1.13–1.25 mm; maximum thoracic depth 1.1–1.2 mm. Color: Antennae with first four segments and apex of last one yellowish, the rest dark or partially dark; body dark, except fore legs, middle legs, elytra, tibiae and tarsi of posterior legs yellowish; however, some specimens may vary from all body yellowish to dark. Vestiture: Body with mixed black, yellowish, and white pubescence; fore coxa with a tuft of white setae; pygidium with basal central spot of white pubescence. Head: Short and broad, densely micropunctulate, frons with a strong median carina, distance between eyes 1.95–2.8× as wide as eye width, eye cleft 0.60–0.71× its length by ocular sinus, posterior margin of eye protruding from adjacent surfaces, postocular lobe rounded and setose; distance from base of antennae to apex of labrum 0.45–0.53× as long as distance from upper limits of eyes to apex of labrum; antennomeres I–III filiform, IV subserrate, V–XI pectinate; antennomere II 2–2.0× as long as antennomere 11; antennomere VII 1.76–2.0× wider that long; antenna extending to mid body. Prothorax: Subconical, without lateral carina; densely foveolate, disc convex, indistinctly gibbous before scutellum and without shallow median channel; prosternal process narrow, triangular, acute, half as long as procoxae. Meso- and metathorax: Scutellum square, bidentate apically; elytra with strial punctures wider than the stria, striae 4 and 5 abbreviated basally by tubercle, humeri slightly raised. Legs: First protarsomere 1.33–1.79× as long as second, first mesotarsomere 2.0–2.1× as long as second, first metatarsomere 2.6–3.2× as long as second; metacoxa densely punctate; hind femur constricted basally and apically, expanded medially to about width of coxa; without external carina ventrally; internal ventral carina with subapical acuminate spine about as long as width of tibial base; hind tibia straight, enlarged, with complete set of carinae; tibial corona with one spinule, the others obsolete, mucro 0.18–0.24× as long as first tarsomere; without sinus at base of spine; first hind tarsomere with ventrolateral glabrous longitudinal carina. Abdomen: Pygidium vertical (Fig. 6); last sternite emarginate. Genitalia: Median lobe moderately long, ventral valve triangular and deeply arcuate, internal sac lined with many small spines, basal portion with a dentiform sclerite and a small spinules forming a triangle (Fig. 7a); lateral lobes elongate, expanded at apex, cleft about 0.73 their length; basal strut with a strong perpendicular keel (Fig. 7b). Female (Fig. 8a–b). Length (pronotum-elytra) 1.85–2.05 mm, width: 1.12–1.3 mm, Maximum thoracic depth 0.95–1.41 mm. Similar to male except antennae serrate; pygidium subvertical; last sternite not marginate.

Figure 5.

Male habitus of ; a dorsal view b lateral view.

Figure 6.

Male pygidium of .

Figure 7.

Male genitalia of ; a median lobe b lateral lobes.

Figure 8.

Female habitus of ; a dorsal view b lateral view.

Host plant.

Unknown.

Kenya and South Africa.

Etymology.

The specific epithet honors the grandaughter of the author, Luna Nereida Nila Romero.

Diagnosis.

This species is included in the genus because it presents all characters indicated in the diagnosis of the genus; also it can be separated from the other two species in the genus because the typical male pygidium, less strongly male antennae, unique armature of the internal sac of male genitalia, and lateral lobes of which bear a basal strut with a strong perpendicular keel.

(Pic, 1912)

Walker, 1859: 261 (homonymy);

Pic, 1912: 92 (replacement name),

:

:

Male (Fig. 9a–b). Length (pronotum-elytra): 1.77–2.1 mm; width: 1.27–1.37 mm; maximum thoracic depth 1.07–1.32 mm. Color: Antennae with the first five segments and apex of the last one yellowish, the rest dark or partially dark; body dark, except fore legs, middle legs, part of elytra, and ventral portion of femora; however some specimens may vary from all body yellowish to dark. Vestiture: Body with mixed black, yellowish, and white pubescence; fore coxa with a tuft of white setae; pygidium with three basal spots of white pubescence, the lateral ones bigger than median. Head: Short and broad, densely micropunctulate, frons with a strong median carina, distance between eyes 1.53–3.3× as wide as eye width, eye cleft 0.57–0.8× its length by ocular sinus, posterior margin of eye protruding from adjacent surfaces, postocular lobe rounded and setose; distance from base of antennae to apex of labrum 0.38–0.47× as long as distance from upper limits of eyes to apex of labrum; antennomeres I–III filiform, IV subserrate, V–XI pectinate; antennomere II 2–2.0× as long as antennomere 11; antennomere VII 4.75–6.67× wider that long; antenna extending to mid body. Prothorax: Subconical, without lateral carina; densely foveolate, disc convex, lightly gibbous before scutellum and without shallow median channel; prosternal process narrow, triangular, acute, half as long as procoxa. Meso- and metathorax: Scutellum square, bidentate apically; elytra with striael punctures as wide as the stria, striae 4 and 5 abbreviated basally by tubercle, humeri slightly raised. Legs: First protarsomere 1.45–1.7× as long as second, first mesotarsomere 1.92–2.6× as long as second, first metatarsomere 2.86–3.4× as long as second; metacoxa densely punctate; hind femur constricted basally and apically, expanded medially to about width of metacoxa; without external carina ventrally; internal ventral carina with subapical acuminate spine about as long as width of tibial base, followed by 2 smaller spines; hind tibia straight, enlarged, with complete set of carinae; tibial corona with 4 spinules, mucro 0.11–0.16× as long as first tarsomere; without sinus at base of spine; first hind tarsomere with ventrolateral glabrous lonPageBreakPageBreakPageBreakPageBreakgitudinal carina. Abdomen: Pygidium vertical (Fig. 10); last sternite emarginate. Genitalia: Median lobe moderately long, ventral valve triangular and deeply arcuate, internal sac lined with many small spines, basal portion with a small spinules forming a triangle (Fig. 11a); lateral lobes elongate, expanded at apex, cleft about 0.66 their length; basal strut with small perpendicular keel (Fig. 11b). Female (Fig. 12a–b). Length (pronotum-elytra) 1.95–2.8 mm, width: 1.25–1.8 mm, Maximum thoracic depth 1.12 mm. Similar to male except antennae serrate; pygidium subvertical; last sternite not marginate.

Figure 9.

Male habitus of ; a dorsal view b lateral view.

Figure 10.

Male pygidium of .

Figure 11.

Male genitalia of ; a median lobe b lateral lobes.

Figure 12.

Female habitus of ; a dorsal view b lateral view.

INDIA: Maharashtra, Lonavla, 28/IV/2000, 650 m, Pacholatko P. (1 ex., CEAM). KENYA: M. Elgon, 24/I/1979, 1950 m, Palm T. (1 ex., MZLU). SRI LANKA: Vayiriuttu, 5 mi W Trincomalee, Estern Prov., 9/II/1962, Lund University Ceylon Expedition, sweeping at teak plantation (1 ex., MZLU); Kuda Oya, 15 mi S Wellawaya, Uva Prov., 22/III/1962, Brinck, Andersson & Cederholm (2 ex., MZLU); Yakkala, 18 mi NE Colombo Western Prov., 26/III/1926, Brinck, Andersson & Cederholm, swept on vegetation at ditches in paddy fields (1 ex., MZLU).

Unknown.

India, Kenya, Sri Lanka, Thailand.

There is little information about this species. At this time its host plants are unknown and only a few specimens were available for study; three of which were still named .

Cladistics

A default tree (Fig. 13) and a consensus tree (Fig. 14) were generated with Mesquite (Maddison and Maddison 2015). The shortest and most parsimonius tree obtained with Henning86 using ie- algorithm is shown in Fig. 15. This tree was the shortest and the most parsimonious with a length of 33, consistency index of 87, and retention index of 81. In total, this cladogram was formed by 26 synapomorphies, 8 parallelisms, and 3 reversals. The tree generated with Hennig86 seems the most reliable to explain the phylogenetic hypothesis about of bruchids with pectinate antennae where males and females share the character; however, the consensus tree generated with Mesquite program has similarities with the Hennig86 tree.

Figure 13.

Default tree generated with Mesquite program.

Figure 14.

Consensus tree generated with Mesquite program.

Figure 15.

Phylogenetic tree generated with Hennig86 program.

In the cladogram in Figure 15 can be seen that each one of the clades corresponds to a different taxon of the family and one of the richest in terms of the number of genera was the clade. This cladogram also supports the hypothesis of host preference, for example the species of the clade feed on seeds of the (palms), on seeds of the , and on seeds of the .

1	Pygidium with one or two tergites exposed behind elytra; antenae in males pectinate or strongly serrate, in female serrate	Kytorhinus Bridwell
–	Pygidium covered at base by elytra	2
2	Tenth elytral stria shortened, extending to middle of elytron; antennae in males pectinate, in female serrate	Megacerus Fahraeus
–	Tenth elytral stria extending nearly to apex of elytron	3
3	Hind femur bicarinate, with spine on both internal and external ventral margins; antennae in males strongly serrate or pectinate, in female subserrate or serrate	Callosobruchus Pic
–	Hind femur not bicarinate or carinae obsolete, or only ventral carina present	4
4	Pronotum conical with distinctly concave sides, antennae in males serrate or pectinate, in female subserrate	Conicobruchus Decelle
–	Pronotum not conical, without distinctly concave sides	5
5	Last antennal segment as long as or longer than hind tibia	6
–	Last antennal segment about half as longer as hind tibia	Decellebruchus Borowiec
6	Hind tibia carinate, mucro longer than lateral coronal denticle; scutellum subcuadrate	Rhipibruchus Bridwell
–	Hind tibia with obsolete lateral carina, mucro absent; scutellum elongate	Pectinibruchus Kingsolver

1	Hind femur with only 1 subapical spine	2
–	Hind femur with 1 subapical spine followed by 2 smaller spines	Decellebruchus walkeri (Pic)
2	Pygidium with basal spot of white pubescence; antennomere VII 1.76-2.0X wider that longer; hind femur with subapical acuminate spine about as long as width of tibial base	Decellebruchus lunae Romero, sp. n.
–	Pygidium with two pubescent spots apically; antennomere VII 4.4-5.6X wider than longer; hind femur with small subapical acuminate spine about half as long as width of tibial base	Decellebruchus atrolineatus (Pic)